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Artykuły w czasopismach na temat „Femtosecond Time-resolved Raman Spectroscopy”

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Data publikacji: 6 września 2023

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1

Lavorel, Bruno, Ha Tran, Edouard Hertz, Olivier Faucher, Pierre Joubert, Marcus Motzkus, Tiago Buckup i in. "Femtosecond Raman time-resolved molecular spectroscopy". Comptes Rendus Physique 5, nr 2 (marzec 2004): 215–29. http://dx.doi.org/10.1016/j.crhy.2004.01.013.

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2

KOBAYASHI, Takayoshi, i Masayuki YOSHIZAWA. "Femtosecond Time-Resolved Stimulated Raman Gain Spectroscopy in Polydiacetylene." Journal of Photopolymer Science and Technology 6, nr 2 (1993): 253–54. http://dx.doi.org/10.2494/photopolymer.6.253.

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3

Yoshizawa, Masayuki, Yasuhiro Hattori i Takayoshi Kobayashi. "Femtosecond time-resolved resonance Raman gain spectroscopy in polydiacetylene". Physical Review B 49, nr 18 (1.05.1994): 13259–62. http://dx.doi.org/10.1103/physrevb.49.13259.

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4

Namboodiri, Mahesh, Tahirzeb Khan, Khadga Karki, Mehdi Mohammad Kazemi, Sidhant Bom, Günter Flachenecker, Vinu Namboodiri i Arnulf Materny. "Nonlinear spectroscopy in the near-field: time resolved spectroscopy and subwavelength resolution non-invasive imaging". Nanophotonics 3, nr 1-2 (1.04.2014): 61–73. http://dx.doi.org/10.1515/nanoph-2013-0044.

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AbstractThe combination of near-field microscopy along with nonlinear optical spectroscopic techniques is presented here. The scanning near-field imaging technique can be integrated with nonlinear spectroscopic techniques to improve spatial and axial resolution of the images. Additionally, ultrafast dynamics can be probed down to nano-scale dimension. The review shows some examples for this combination, which resulted in an exciton map and vibrational contrast images with sub-wavelength resolution. Results of two-color femtosecond time-resolved pump-probe experiments using scanning near-field optical microscopy (SNOM) on thin films of the organic semiconductor 3,4,9,10 Perylenetetracarboxylic dianhydride (PTCDA) are presented. While nonlinear Raman techniques have been used to obtain highly resolved images in combination with near-field microscopy, the use of femtosecond laser pulses in electronic resonance still constitutes a big challenge. Here, we present our first results on coherent anti-Stokes Raman scattering (fs-CARS) with femtosecond laser pulses detected in the near-field using SNOM. We demonstrate that highly spatially resolved images can be obtained from poly(3-hexylthiophene) (P3HT) nano-structures where the fs-CARS process was in resonance with the P3HT absorption and with characteristic P3HT vibrational modes without destruction of the samples. Sub-diffraction limited lateral resolution is achieved. Especially the height resolution clearly surpasses that obtained with standard microCARS. These results will be the basis for future investigations of mode-selective dynamics in the near-field.

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5

Towrie, Michael, Anders Gabrielsson, Pavel Matousek, Anthony W. Parker, Ana Maria Blanco Rodriguez i Antonín Vlček. "A High-Sensitivity Femtosecond to Microsecond Time-Resolved Infrared Vibrational Spectrometer". Applied Spectroscopy 59, nr 4 (kwiecień 2005): 467–73. http://dx.doi.org/10.1366/0003702053641397.

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We describe an apparatus that provides, for the first time, a seamless bridge between femtosecond and microsecond time-resolved Raman and infrared vibrational spectroscopy. The laser system comprises an actively Q-switched sub-nanosecond pulsed kilohertz laser electronically synchronized to an ultrafast titanium sapphire regenerative amplifier to within 0.2 ns. The ultrafast amplifier provides the stable probe light source enabling high-sensitivity infrared vibrational spectroscopy of transients. Time-resolved infrared spectra of the excited-state relaxation dynamics of metal carbonyl compounds are presented to illustrate the capability of the apparatus, and transient data is resolved from 1 picosecond to over 100 microseconds. The results are compared to conventional nanosecond Fourier transform infrared (FT-IR) and laser based flash photolysis time-resolved infrared technology.

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6

Zhao, Yang, Sheng Zhang, Boyang Zhou, Rongwei Fan, Deying Chen, Zhonghua Zhang i Yuanqin Xia. "Molecular vibrational dynamics in PMMA studied by femtosecond CARS". Modern Physics Letters B 28, nr 28 (10.11.2014): 1450222. http://dx.doi.org/10.1142/s0217984914502224.

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The ultrafast molecular vibrational dynamics in PMMA sheets is studied by femtosecond time-resolved coherent anti-Stokes Raman spectroscopy at room temperature. The C – H stretch modes at 2870 cm-1 and 3008 cm-1 in PMMA sheets are excited and detected. The coherence relaxation times and beat wavenumbers of the Raman modes are obtained.

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7

Jen, Myungsam, Sebok Lee, Gisang Lee, Daedu Lee i Yoonsoo Pang. "Intramolecular Charge Transfer of Curcumin and Solvation Dynamics of DMSO Probed by Time-Resolved Raman Spectroscopy". International Journal of Molecular Sciences 23, nr 3 (2.02.2022): 1727. http://dx.doi.org/10.3390/ijms23031727.

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Intramolecular charge transfer (ICT) of curcumin in dimethyl sulfoxide (DMSO) solution in the excited state was investigated by femtosecond electronic and vibrational spectroscopy. Excited-state Raman spectra of curcumin in the locally-excited and charge-transferred (CT) state of the S1 excited state were separated due to high temporal (<50 fs) and spectral (<10 cm−1) resolutions of femtosecond stimulated Raman spectroscopy. The ultrafast (0.6–0.8 ps) ICT and subsequent vibrational relaxation (6–9 ps) in the CT state were ubiquitously observed in the ground- and excited-state vibrational modes of the solute curcumin and the νCSC and νS=O modes of solvent DMSO. The ICT of curcumin in the excited state was preceded by the disruption of the solvation shells, including the breakage of hydrogen bonding between curcumin and DMSO molecules, which occurs at the ultrafast (20–50 fs) time scales.

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8

Holzapfel, W., R. Leonhardt i W. Zinth. "The influence of phase-modulation on femtosecond time-resolved coherent Raman spectroscopy". Applied Physics B Photophysics and Laser Chemistry 47, nr 4 (grudzień 1988): 307–12. http://dx.doi.org/10.1007/bf00716091.

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9

Takaya, Tomohisa, i Koichi Iwata. "Development of a femtosecond time-resolved near-IR multiplex stimulated Raman spectrometer in resonance with transitions in the 900–1550 nm region". Analyst 141, nr 14 (2016): 4283–92. http://dx.doi.org/10.1039/c6an01051b.

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10

Liu, Yingliang, Aditya S. Chaudhari, Aditi Chatterjee, Prokopis C. Andrikopoulos, Alessandra Picchiotti, Mateusz Rebarz, Miroslav Kloz, Victor A. Lorenz-Fonfria, Bohdan Schneider i Gustavo Fuertes. "Sub-Millisecond Photoinduced Dynamics of Free and EL222-Bound FMN by Stimulated Raman and Visible Absorption Spectroscopies". Biomolecules 13, nr 1 (12.01.2023): 161. http://dx.doi.org/10.3390/biom13010161.

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Time-resolved femtosecond-stimulated Raman spectroscopy (FSRS) provides valuable information on the structural dynamics of biomolecules. However, FSRS has been applied mainly up to the nanoseconds regime and above 700 cm−1, which covers only part of the spectrum of biologically relevant time scales and Raman shifts. Here we report on a broadband (~200–2200 cm−1) dual transient visible absorption (visTA)/FSRS set-up that can accommodate time delays from a few femtoseconds to several hundreds of microseconds after illumination with an actinic pump. The extended time scale and wavenumber range allowed us to monitor the complete excited-state dynamics of the biological chromophore flavin mononucleotide (FMN), both free in solution and embedded in two variants of the bacterial light-oxygen-voltage (LOV) photoreceptor EL222. The observed lifetimes and intermediate states (singlet, triplet, and adduct) are in agreement with previous time-resolved infrared spectroscopy experiments. Importantly, we found evidence for additional dynamical events, particularly upon analysis of the low-frequency Raman region below 1000 cm−1. We show that fs-to-sub-ms visTA/FSRS with a broad wavenumber range is a useful tool to characterize short-lived conformationally excited states in flavoproteins and potentially other light-responsive proteins.

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11

Bilal, Syed M., Surajit Kayal, Krishnankutty S. Sanju i Y. Adithya Lakshmanna. "Femtosecond Time-Resolved Raman Spectroscopy Reveals Structural Evidence for meta Effect in Stilbenols". Journal of Physical Chemistry A 122, nr 19 (23.04.2018): 4601–8. http://dx.doi.org/10.1021/acs.jpca.7b12339.

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12

Rouzée, A., V. Boudon, B. Lavorel, O. Faucher i W. Raballand. "Rotational Raman spectroscopy of ethylene using a femtosecond time-resolved pump-probe technique". Journal of Chemical Physics 123, nr 15 (15.10.2005): 154309. http://dx.doi.org/10.1063/1.2069866.

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13

Takaya, Tomohisa, Ippei Enokida, Yukio Furukawa i Koichi Iwata. "Direct Observation of Structure and Dynamics of Photogenerated Charge Carriers in Poly(3-hexylthiophene) Films by Femtosecond Time-Resolved Near-IR Inverse Raman Spectroscopy". Molecules 24, nr 3 (25.01.2019): 431. http://dx.doi.org/10.3390/molecules24030431.

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The initial charge separation process of conjugated polymers is one of the key factors for understanding their conductivity. The structure of photogenerated transients in conjugated polymers can be observed by resonance Raman spectroscopy in the near-IR region because they exhibit characteristic low-energy transitions. Here, we investigate the structure and dynamics of photogenerated transients in a regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend film, as well as in a pristine P3HT film, using femtosecond time-resolved resonance inverse Raman spectroscopy in the near-IR region. The transient inverse Raman spectrum of the pristine P3HT film at 50 ps suggests coexistence of neutral and charged excitations, whereas that of the P3HT:PCBM blend film at 50 ps suggests formation of positive polarons with a different structure from those in an FeCl3-doped P3HT film. Time-resolved near-IR inverse Raman spectra of the blend film clearly show the absence of charge separation between P3HT and PCBM within the instrument response time of our spectrometer, while they indicate two independent pathways of the polaron formation with time constants of 0.3 and 10 ps.

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14

Kimberg, Victor, Alvaro Sanchez-Gonzalez, Laurent Mercadier, Clemens Weninger, Alberto Lutman, Daniel Ratner, Ryan Coffee i in. "Stimulated X-ray Raman scattering – a critical assessment of the building block of nonlinear X-ray spectroscopy". Faraday Discussions 194 (2016): 305–24. http://dx.doi.org/10.1039/c6fd00103c.

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With the invention of femtosecond X-ray free-electron lasers (XFELs), studies of light-induced chemical reaction dynamics and structural dynamics reach a new era, allowing for time-resolved X-ray diffraction and spectroscopy. To ultimately probe coherent electron and nuclear dynamics on their natural time and length scales, coherent nonlinear X-ray spectroscopy schemes have been proposed. In this contribution, we want to critically assess the experimental realisation of nonlinear X-ray spectroscopy at current-day XFEL sources, by presenting first experimental attempts to demonstrate stimulated resonant X-ray Raman scattering in molecular gas targets.

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15

Kim, Hyung Min, Hyunmin Kim, Ilseung Yang, Seung Min Jin i Yung Doug Suh. "Time-gated pre-resonant femtosecond stimulated Raman spectroscopy of diethylthiatricarbocyanine iodide". Phys. Chem. Chem. Phys. 16, nr 11 (2014): 5312–18. http://dx.doi.org/10.1039/c3cp54870h.

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16

Keller, Emily L., Nathaniel C. Brandt, Alyssa A. Cassabaum i Renee R. Frontiera. "Ultrafast surface-enhanced Raman spectroscopy". Analyst 140, nr 15 (2015): 4922–31. http://dx.doi.org/10.1039/c5an00869g.

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17

McCamant, David W., Philipp Kukura i Richard A. Mathies. "Femtosecond Time-Resolved Stimulated Raman Spectroscopy: Application to the Ultrafast Internal Conversion in β-Carotene†". Journal of Physical Chemistry A 107, nr 40 (październik 2003): 8208–14. http://dx.doi.org/10.1021/jp030147n.

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18

Kukura, Philipp, David W. McCamant i Richard A. Mathies. "Femtosecond Time-Resolved Stimulated Raman Spectroscopy of the S2(1Bu+) Excited State of β-Carotene". Journal of Physical Chemistry A 108, nr 28 (lipiec 2004): 5921–25. http://dx.doi.org/10.1021/jp0482971.

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19

Takaya, Tomohisa, Masato Anan i Koichi Iwata. "Vibrational relaxation dynamics of β-carotene and its derivatives with substituents on terminal rings in electronically excited states as studied by femtosecond time-resolved stimulated Raman spectroscopy in the near-IR region". Physical Chemistry Chemical Physics 20, nr 5 (2018): 3320–27. http://dx.doi.org/10.1039/c7cp06343a.

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20

Niu, Kai, i Soo-Y. Lee. "Analysis of time resolved femtosecond and femtosecond/picosecond coherent anti-Stokes Raman spectroscopy: Application to toluene and Rhodamine 6G". Journal of Chemical Physics 136, nr 6 (14.02.2012): 064504. http://dx.doi.org/10.1063/1.3682470.

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21

Du, Lili, Zhiping Yan, Xueqin Bai, Runhui Liang i David Lee Phillips. "Time-Resolved Spectroscopic Study of N,N–Di(4–bromo)nitrenium Ions in Acidic Aqueous Solution". International Journal of Molecular Sciences 20, nr 21 (5.11.2019): 5512. http://dx.doi.org/10.3390/ijms20215512.

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Nitrenium ions are common reactive intermediates with high activities towards some biological nucleophiles. In this paper, we employed femtosecond transient absorption (fs-TA) and nanosecond transient absorption (ns-TA) as well as nanosecond time-resolved resonance Raman (ns-TR3) spectroscopy and density function theory (DFT) calculations to study the spectroscopic properties of the N(4,4′–dibromodiphenylamino)–2,4,6–trimethylpyridinium BF4− salt (1) in an acidic aqueous solution. Efficient cleavage of the N–N bond (4 ps) to form the N,N–di(4–bromophenyl)nitrenium ion (DN) was also observed in the acidic aqueous solution. As a result, the dication intermediate 4 appears more likely to be produced after abstracting a proton for the nitrenium ion DN in the acid solution first, followed by an electron abstraction to form the radical cation intermediate 3. These new and more extensive time-resolved spectroscopic data will be useful to help to develop an improved understanding of the identity, nature, and properties of nitrenium ions involved in reactions under acidic aqueous conditions.

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22

Zhang, Wei, Jie Kong, Wenqi Xu, Xinmiao Niu, Di Song, Weimin Liu i Andong Xia. "Probing effect of solvation on photoexcited quadrupolar donor-acceptor-donor molecule via ultrafast Raman spectroscopy". Chinese Journal of Chemical Physics 35, nr 1 (luty 2022): 69–76. http://dx.doi.org/10.1063/1674-0068/cjcp2111223.

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The symmetric and quadrupolar donor-acceptor-donor (D-A-D) molecules usually exhibit excited-state charge redistribution process from delocalized intramolecular charge transfer (ICT) state to localized ICT state. Direct observation of such charge redistribution process in real-time has been intensively studied via various ultrafast time-resolved spectroscopies. Femtosecond stimulated Raman spectroscopy (FSRS) is one of the powerful methods which can be used to determine the excited state dynamics by tracking vibrational mode evolution of the specific chemical bonds within molecules. Herein, a molecule, 4,4′-(buta-1,3-diyne-1,4-diyl)bis( N, N-bis(4-methoxyphenyl)aniline), that consists of two central adjacent alkyne (-C≡C-) groups as electron-acceptors and two separated, symmetric N, N-bis(4-methoxyphenyl)aniline at both branches as electron-donors, is chosen to investigate the excited-state photophysical properties. It is shown that the solvation induced excited-state charge redistribution in polar solvents can be probed by using femtosecond stimulated Raman spectroscopy. The results provide a fundamental understanding of photoexcitation induced charge delocalization/localization properties of the symmetric quadrupolar molecules with adjacent vibrational markers located at central position.

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23

Song, Yunfei, Honglin Wu, Gangbei Zhu, Yangyang Zeng, Guoyang Yu i Yanqiang Yang. "A femtosecond time-resolved coherent anti-Stokes Raman spectroscopy thermometry for steady-state high-temperature flame". Combustion and Flame 242 (sierpień 2022): 112166. http://dx.doi.org/10.1016/j.combustflame.2022.112166.

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24

Joo, Taiha, i A. C. Albrecht. "Femtosecond time‐resolved coherent anti‐Stokes Raman spectroscopy of liquid benzene: A Kubo relaxation function analysis". Journal of Chemical Physics 99, nr 5 (wrzesień 1993): 3244–51. http://dx.doi.org/10.1063/1.466194.

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25

Yamaguchi, Shoichi, i Hiro-o. Hamaguchi. "Ultrafast vibrational relaxation in photogenerated S1 α-terthiophene in solution by femtosecond time-resolved absorption/emission and picosecond time-resolved Raman spectroscopy". Chemical Physics Letters 227, nr 3 (wrzesień 1994): 255–60. http://dx.doi.org/10.1016/0009-2614(94)00832-9.

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26

Saltarelli, Francesco, Vikas Kumar, Daniele Viola, Francesco Crisafi, Fabrizio Preda, Giulio Cerullo i Dario Polli. "Photonic Time-Stretch Spectroscopy for Multiplex Stimulated Raman Scattering". EPJ Web of Conferences 205 (2019): 03003. http://dx.doi.org/10.1051/epjconf/201920503003.

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Stimulated Raman scattering spectroscopy enables label-free molecular identification, but its broadband implementation is technically challenging. We experimentally demonstrate a novel approach to multiplex stimulated Raman scattering based on photonic time stretch. A telecom fiber stretches the broadband femtosecond Stokes pulse after the sample to ∼15ns, mapping its spectrum in time. The signal is sampled through a fast oscilloscope, providing single-shot spectra at 80-kHz rate. We demonstrate high sensitivity in detecting the Raman vibrational modes of various samples over the entire high-frequency C-H stretching region. Our results pave the way to high-speed broadband vibrational imaging for materials science and biophotonics.

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27

OCKMAN, NATHAN, WUBAO WANG i R. R. ALFANO. "APPLICATIONS OF ULTRAFAST LASER SPECTROSCOPY TO THE STUDY OF SEMICONDUCTOR PHYSICS". International Journal of Modern Physics B 05, nr 20 (grudzień 1991): 3165–234. http://dx.doi.org/10.1142/s0217979291001255.

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This article reviews the application of some of the principal methods of picosecond and femtosecond laser spectroscopy to the investigation of the dynamics of carriers, phonons and surface structure in semiconductors. The measurement of the temporal evolution of photoinduced luminescence, absorption, reflection and scattering in semiconductors makes it possible to obtain the lifetimes of photogenerated electrons, holes, excitons and phonons in both the bulk and quantum wells and superlattice structures. The information produced by these studies is necessary for the basic understanding of the underlying physics of semiconductors. In addition, the parameters obtained from these studies are needed for evaluating ultrafast transport, switching, photoconductive response and imaging in semiconductor materials, which will determine their limitations for use in high-speed and high-frequency devices and computers. For measuring time resolved luminescence, the principal techniques used, namely, the streak camera, the optical Kerr gate and the up-conversion gate are thoroughly discussed. Several pump and probe methods are described for the determination of time resolved absorption, reflection and Raman scattering. For absorption measurements where the probe wavelength differs from the pump, the former is generated in nonlinear media by means of stimulated Raman scattering and the supercontinuum for the UV and visible regions and by parametric and difference frequency generation for the near- and mid-IR. Nonlinear optics techniques considered are degenerate and nondegenerate four-wave mixing and transient grattings among which photon echoes yield the momentum relaxation of hot electrons. Coherent anti-Stokes Raman scattering (CARS) and phase conjugate Raman scattering (PC) are described to determine phonon dephasing times and the nonlinear susceptibility, χ3.

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28

Roy, Sukesh, Paul J. Kinnius, Robert P. Lucht i James R. Gord. "Temperature measurements in reacting flows by time-resolved femtosecond coherent anti-Stokes Raman scattering (fs-CARS) spectroscopy". Optics Communications 281, nr 2 (styczeń 2008): 319–25. http://dx.doi.org/10.1016/j.optcom.2007.09.040.

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29

Zhao, Bin, Zhigang Sun i Soo-Y. Lee. "Quantum theory of time-resolved femtosecond stimulated Raman spectroscopy: Direct versus cascade processes and application to CDCl3". Journal of Chemical Physics 134, nr 2 (14.01.2011): 024307. http://dx.doi.org/10.1063/1.3525100.

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30

Du, Lili, Xin Lan, Zhiping Yan, Ruixue Zhu i David Phillips. "Time-Resolved Spectroscopic Study of N,N-Di(4-bromo)nitrenium Ions in Selected Solutions". Molecules 23, nr 12 (3.12.2018): 3182. http://dx.doi.org/10.3390/molecules23123182.

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Nitrenium ions are important reactive intermediates in chemistry and biology. In this work, femtosecond and nanosecond transient absorption (fs-TA and ns-TA) along with nanosecond time-resolved resonance Raman (ns-TR3) experiments were employed to examine the photochemical pathways of N-(4,4′-dibromodiphenylamino)-2,4,6-trimethylpyridinium BF4− (salt (DN) from just absorption of a photon of light to the production of the important N,N-di(4-bromophenyl)nitrenium ion 2. In acetonitrile (MeCN), the formation of halogenated diarylnitrenium ion 2 was observed within 4 ps, showing the vibrational spectra with strong intensity. The nucleophilic adduct reaction of ion 2 with H2O was also examined in aqueous solutions. The direct detection of the unique ortho adduct intermediate 3 shows that there is an efficient and exclusive reaction pathway for 2 with H2O. The results shown in this paper give new characterization of 2, which can be used to design time-resolved spectroscopy investigations of covalent addition reactions of nitrenium ions with other molecules in future studies.

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31

Ariunbold, Gombojav O., Bryan Semon, Supriya Nagpal i Prakash Adhikari. "Coherent Anti-Stokes–Stokes Raman Cross-Correlation Spectroscopy: Asymmetric Frequency Shifts in Hydrogen-Bonded Pyridine-Water Complexes". Applied Spectroscopy 73, nr 9 (11.07.2019): 1099–106. http://dx.doi.org/10.1177/0003702819857771.

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Hydrogen bonding is a vital molecular interaction for bio-molecular systems, yet deep understanding of its ways of creating various complexes requires extensive empirical testing. A hybrid femtosecond/picosecond coherent Raman spectroscopic technique is applied to study pyridine-water complexes. Both the coherent Stokes and anti-Stokes Raman spectra are recorded simultaneously as the concentration of water in pyridine varied. A 3 ps and 10 cm−1 narrowband probe pulse enables us to observe well-resolved Raman spectra. The hydrogen bonding between pyridine and water forms the complexes that have altered vibrational frequencies. These red and blue shifts were observed to be uneven. This asymmetry was result of the generated background nonlinear optical processes of pyridine-water complexes. This asymmetry tends to disappear as probe pulse further delayed attaining background-free coherent Raman spectra. For better visualization, spectral analyses both traditional two-dimensional correlation spectroscopy and recent second-order correlation functions defined in frequency domain are employed. Recognized as a label-free and background-free technique, the coherent Raman spectroscopy, complemented with a known high-resolution spectroscopic correlation analysis, has potential in studying the hydrogen-bonded pyridine-water complexes. These complexes are of great biological importance both due to the ubiquitous nature of hydrogen bonds and due to the close resemblance to chemical bases in macro-biomolecules.

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32

JOO, T., i A. C. ALBRECHT. "ChemInform Abstract: Femtosecond Time-Resolved Coherent Anti-Stokes Raman Spectroscopy of Liquid Benzene: A Kubo Relaxation Function Analysis." ChemInform 24, nr 52 (19.08.2010): no. http://dx.doi.org/10.1002/chin.199352039.

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33

Ceraso, Arianna, Sen Mou, Andrea Rubano i Domenico Paparo. "Coherent THz Hyper-Raman: Spectroscopy and Application in THz Detection". Materials 12, nr 23 (23.11.2019): 3870. http://dx.doi.org/10.3390/ma12233870.

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Recently we have demonstrated a new nonlinear optical effect in the THz interval of frequencies. The latter is based on the use of femtosecond optical pulses and intense, sub-ps, broadband terahertz (THz) pulses to generate a THz-optical four- and five-wave mixing in the investigated material. The spectrum of the generated signal is resolved in time and wavelength and displays two pronounced frequency sidebands, Stokes and anti-Stokes, close to the optical second harmonic central frequency 2 ω L , where ω L is the optical central frequency of the fundamental beam, thus resembling the spectrum of standard hyper-Raman scattering, and hence we named this effect ‘THz hyper-Raman’—THYR. We applied this technique to several crystalline materials, including α-quartz and gallium selenide. In the first material, we find that the THYR technique brings spectroscopic information on a large variety of low-energy excitations that include polaritons and phonons far from the Γ-point, which are difficult to study with standard optical techniques. In the second example, we show that this new tool offers some advantages in detecting ultra-broadband THz pulses. In this paper we review these two recent results, showing the potentialities of this new THz technique.

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Xie, Junhan, Ziyu Wang, Ruixue Zhu, Jiaming Jiang, Tsu-Chien Weng, Yi Ren, Shuhua Han, Yifan Huang i Weimin Liu. "Investigation of Excited-State Intramolecular Proton Transfer and Structural Dynamics in Bis-Benzimidazole Derivative (BBM)". International Journal of Molecular Sciences 24, nr 11 (29.05.2023): 9438. http://dx.doi.org/10.3390/ijms24119438.

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The bis-benzimidazole derivative (BBM) molecule, consisting of two 2-(2′-hydroxyphenyl) benzimidazole (HBI) halves, has been synthesized and successfully utilized as a ratiometric fluorescence sensor for the sensitive detection of Cu2+ based on enol–keto excited-state intramolecular proton transfer (ESIPT). In this study, we strategically implement femtosecond stimulated Raman spectroscopy and several time-resolved electronic spectroscopies, aided by quantum chemical calculations to investigate the detailed primary photodynamics of the BBM molecule. The results demonstrate that the ESIPT from BBM-enol* to BBM-keto* was observed in only one of the HBI halves with a time constant of 300 fs; after that, the rotation of the dihedral angle between the two HBI halves generated a planarized BBM-keto* isomer in 3 ps, leading to a dynamic redshift of BBM-keto* emission.

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Bailey-Darland, Sullivan, Taylor D. Krueger i Chong Fang. "Ultrafast Spectroscopies of Nitrophenols and Nitrophenolates in Solution: From Electronic Dynamics and Vibrational Structures to Photochemical and Environmental Implications". Molecules 28, nr 2 (6.01.2023): 601. http://dx.doi.org/10.3390/molecules28020601.

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Nitrophenols are a group of small organic molecules with significant environmental implications from the atmosphere to waterways. In this work, we investigate a series of nitrophenols and nitrophenolates, with the contrasting ortho-, meta-, and para-substituted nitro group to the phenolic hydroxy or phenolate oxygen site (2/3/4NP or NP−), implementing a suite of steady-state and time-resolved spectroscopic techniques that include UV/Visible spectroscopy, femtosecond transient absorption (fs-TA) spectroscopy with probe-dependent and global analysis, and femtosecond stimulated Raman spectroscopy (FSRS), aided by quantum calculations. The excitation-dependent (400 and 267 nm) electronic dynamics in water and methanol, for six protonated or deprotonated nitrophenol molecules (three regioisomers in each set), enable a systematic investigation of the excited-state dynamics of these functional “nanomachines” that can undergo nitro-group twisting (as a rotor), excited-state intramolecular or intermolecular proton transfer (donor–acceptor, ESIPT, or ESPT), solvation, and cooling (chromophore) events on molecular timescales. In particular, the meta-substituted compound 3NP or 3NP− exhibits the strongest charge-transfer character with FSRS signatures (e.g., C–N peak frequency), and thus, does not favor nitroaromatic twist in the excited state, while the ortho-substituted compound 2NP can undergo ESIPT in water and likely generate nitrous acid (HONO) after 267 nm excitation. The delineated mechanistic insights into the nitro-substituent-location-, protonation-, solvent-, and excitation-wavelength-dependent effects on nitrophenols, in conjunction with the ultraviolet-light-induced degradation of 2NP in water, substantiates an appealing discovery loop to characterize and engineer functional molecules for environmental applications.

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Smeigh, Amanda L., Mark Creelman, Richard A. Mathies i James K. McCusker. "Femtosecond Time-Resolved Optical and Raman Spectroscopy of Photoinduced Spin Crossover: Temporal Resolution of Low-to-High Spin Optical Switching". Journal of the American Chemical Society 130, nr 43 (29.10.2008): 14105–7. http://dx.doi.org/10.1021/ja805949s.

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Kruglik, Sergei G., Audrius Jasaitis, Klara Hola, Taku Yamashita, Ursula Liebl, Jean-Louis Martin i Marten H. Vos. "Subpicosecond oxygen trapping in the heme pocket of the oxygen sensor FixL observed by time-resolved resonance Raman spectroscopy". Proceedings of the National Academy of Sciences 104, nr 18 (19.04.2007): 7408–13. http://dx.doi.org/10.1073/pnas.0700445104.

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Dissociation of oxygen from the heme domain of the bacterial oxygen sensor protein FixL constitutes the first step in hypoxia-induced signaling. In the present study, the photodissociation of the heme-O2 bond was used to synchronize this event, and time-resolved resonance Raman (TR3) spectroscopy with subpicosecond time resolution was implemented to characterize the heme configuration of the primary photoproduct. TR3 measurements on heme-oxycomplexes are highly challenging and have not yet been reported. Whereas in all other known six-coordinated heme protein complexes with diatomic ligands, including the oxymyoglobin reported here, heme iron out-of-plane motion (doming) occurs faster than 1 ps after iron–ligand bond breaking; surprisingly, no sizeable doming is observed in the oxycomplex of the Bradyrhizobium japonicum FixL sensor domain (FixLH). This assessment is deduced from the absence of the iron–histidine band around 217 cm−1 as early as 0.5 ps. We suggest that efficient ultrafast oxygen rebinding to the heme occurs on the femtosecond time scale, thus hindering heme doming. Comparing WT oxy-FixLH, mutant proteins FixLH-R220H and FixLH-R220Q, the respective carbonmonoxy-complexes, and oxymyoglobin, we show that a hydrogen bond of the terminal oxygen atom with the residue in position 220 is responsible for the observed behavior; in WT FixL this residue is arginine, crucially implicated in signal transmission. We propose that the rigid O2 configuration imposed by this residue, in combination with the hydrophobic and constrained properties of the distal cavity, keep dissociated oxygen in place. These results uncover the origin of the “oxygen cage” properties of this oxygen sensor protein.

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Brozek-Pluska, Beata, Arkadiusz Jarota, Rafal Kania i Halina Abramczyk. "Zinc Phthalocyanine Photochemistry by Raman Imaging, Fluorescence Spectroscopy and Femtosecond Spectroscopy in Normal and Cancerous Human Colon Tissues and Single Cells". Molecules 25, nr 11 (10.06.2020): 2688. http://dx.doi.org/10.3390/molecules25112688.

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Photodynamic therapy is a clinically approved alternative method for cancer treatment in which a combination of nontoxic drugs known as photosensitizers and oxygen is used. Despite intensive investigations and encouraging results, zinc phthalocyanines (ZnPcs) have not yet been approved as photosensitizers for clinical use. Label-free Raman imaging of nonfixed and unstained normal and cancerous colon human tissues and normal human CCD18-Co and cancerous CaCo-2 cell lines, without and after adding ZnPcS4 photosensitizer, was analyzed. The biochemical composition of normal and cancerous colon tissues and colon cells without and after adding ZnPcS4 at the subcellular level was determined. Analyzing the fluorescence/Raman signals of ZnPcS4, we found that in normal human colon tissue samples, in contrast to cancerous ones, there is a lower affinity to ZnPcS4 phthalocyanine. Moreover, a higher concentration in cancerous tissue was concomitant with a blue shift of the maximum peak position specific for the photosensitizer from 691–695 nm to 689 nm. Simultaneously for both types of samples, the signal was observed in the monomer region, confirming the excellent properties of ZnPcS4 for photo therapy (PDT). For colon cell experiments with a lower concentration of ZnPcS4 photosensitizer, c = 1 × 10−6 M, the phthalocyanine was localized in mitochondria/lipid structures; for a higher concentration, c = 9 × 10−6 M, localization inside the nucleus was predominant. Based on time-resolved experiments, we found that ZnPcS4 in the presence of biological interfaces features longer excited-state lifetime photosensitizers compared to the aqueous solution and bare ZnPcS4 film on CaF2 substrate, which is beneficial for application in PDT.

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Henry, Anne-Isabelle, Tyler W. Ueltschi, Michael O. McAnally i Richard P. Van Duyne. "Spiers Memorial Lecture : Surface-enhanced Raman spectroscopy: from single particle/molecule spectroscopy to ångstrom-scale spatial resolution and femtosecond time resolution". Faraday Discussions 205 (2017): 9–30. http://dx.doi.org/10.1039/c7fd00181a.

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Four decades on, surface-enhanced Raman spectroscopy (SERS) continues to be a vibrant field of research that is growing (approximately) exponentially in scope and applicability while pushing at the ultimate limits of sensitivity, spatial resolution, and time resolution. This introductory paper discusses some aspects related to all four of the themes for this Faraday Discussion. First, the wavelength-scanned SERS excitation spectroscopy (WS-SERES) of single nanosphere oligomers (viz., dimers, trimers, etc.), the distance dependence of SERS, the magnitude of the chemical enhancement mechanism, and the progress toward developing surface-enhanced femtosecond stimulated Raman spectroscopy (SE-FSRS) are discussed. Second, our efforts to develop a continuous, minimally invasive, in vivo glucose sensor based on SERS are highlighted. Third, some aspects of our recent work in single molecule SERS and the translation of that effort to ångstrom-scale spatial resolution in ultrahigh vacuum tip-enhanced Raman spectroscopy (UHV-TERS) and single molecule electrochemistry using electrochemical (EC)-TERS will be presented. Finally, we provide an overview of analytical SERS with our viewpoints on SERS substrates, approaches to address the analyte generality problem (i.e. target molecules that do not spontaneously adsorb and/or have Raman cross sections <10⁻²⁹ cm² sr⁻¹), SERS for catalysis, and deep UV-SERS.

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Lau, A., M. Pfeiffer, V. Kozich i A. Kummrow. "Molecular Dynamics Investigated by Temporally Two-Dimensional Coherent Raman Spectroscopy". Laser Chemistry 19, nr 1-4 (1.01.1999): 35–40. http://dx.doi.org/10.1155/1999/41281.

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A six-wave set-up is described to determine molecular dynamics in the condensed phase. Applying two independent time delays between excitation and probe pulses additional information on the dynamics should be obtainable. We show experimentally that such investigations can be carried out with noisy light having intensity fluctuations in the femtosecond region. As first result we found a fast relaxation time in neat nitrobenzene of 100 fs, becoming even faster in mixtures with low viscosity liquids. Switching on a Raman resonance yields a longer relaxation time, which could be explained by an additional contribution by that vibration.

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Bohlin, Alexis, Markus Mann, Brian D. Patterson, Andreas Dreizler i Christopher J. Kliewer. "Development of two-beam femtosecond/picosecond one-dimensional rotational coherent anti-Stokes Raman spectroscopy: Time-resolved probing of flame wall interactions". Proceedings of the Combustion Institute 35, nr 3 (2015): 3723–30. http://dx.doi.org/10.1016/j.proci.2014.05.124.

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Fang, Chong, i Longteng Tang. "Mapping Structural Dynamics of Proteins with Femtosecond Stimulated Raman Spectroscopy". Annual Review of Physical Chemistry 71, nr 1 (20.04.2020): 239–65. http://dx.doi.org/10.1146/annurev-physchem-071119-040154.

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The structure–function relationships of biomolecules have captured the interest and imagination of the scientific community and general public since the field of structural biology emerged to enable the molecular understanding of life processes. Proteins that play numerous functional roles in cellular processes have remained in the forefront of research, inspiring new characterization techniques. In this review, we present key theoretical concepts and recent experimental strategies using femtosecond stimulated Raman spectroscopy (FSRS) to map the structural dynamics of proteins, highlighting the flexible chromophores on ultrafast timescales. In particular, wavelength-tunable FSRS exploits dynamic resonance conditions to track transient-species-dependent vibrational motions, enabling rational design to alter functions. Various ways of capturing excited-state chromophore structural snapshots in the time and/or frequency domains are discussed. Continuous development of experimental methodologies, synergistic correlation with theoretical modeling, and the expansion to other nonequilibrium, photoswitchable, and controllable protein systems will greatly advance the chemical, physical, and biological sciences.

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Krueger, Taylor D., Longteng Tang i Chong Fang. "Delineating Ultrafast Structural Dynamics of a Green-Red Fluorescent Protein for Calcium Sensing". Biosensors 13, nr 2 (2.02.2023): 218. http://dx.doi.org/10.3390/bios13020218.

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Fluorescent proteins (FPs) are indispensable tools for noninvasive bioimaging and sensing. Measuring the free cellular calcium (Ca2+) concentrations in vivo with genetically encodable FPs can be a relatively direct measure of neuronal activity due to the complex signaling role of these ions. REX-GECO1 is a recently developed red-green emission and excitation ratiometric FP-based biosensor that achieves a high dynamic range due to differences in the chromophore response to light excitation with and without calcium ions. Using steady-state electronic measurements (UV/Visible absorption and emission), along with time-resolved spectroscopic techniques including femtosecond transient absorption (fs-TA) and femtosecond stimulated Raman spectroscopy (FSRS), the potential energy surfaces of these unique biosensors are unveiled with vivid details. The ground-state structural characterization of the Ca2+-free biosensor via FSRS reveals a more spacious protein pocket that allows the chromophore to efficiently twist and reach a dark state. In contrast, the more compressed cavity within the Ca2+-bound biosensor results in a more heterogeneous distribution of chromophore populations that results in multi-step excited state proton transfer (ESPT) pathways on the sub-140 fs, 600 fs, and 3 ps timescales. These results enable rational design strategies to enlarge the spectral separation between the protonated/deprotonated forms and the Stokes shift leading to a larger dynamic range and potentially higher fluorescence quantum yield, which should be broadly applicable to the calcium imaging and biosensor communities.

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Tran, H., F. Chaussard, N. Le Cong, B. Lavorel, O. Faucher i P. Joubert. "Femtosecond time resolved coherent anti-Stokes Raman spectroscopy of H2–N2 mixtures in the Dicke regime: Experiments and modeling of velocity effects". Journal of Chemical Physics 131, nr 17 (7.11.2009): 174310. http://dx.doi.org/10.1063/1.3257640.

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Ariunbold, Gombojav O., Bryan Semon, Supriya Nagpal i Yuri Rostovtsev. "Ultrafast dephasing in hydrogen-bonded pyridine–water mixtures". Open Physics 19, nr 1 (1.01.2021): 234–40. http://dx.doi.org/10.1515/phys-2021-0027.

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Abstract Hydrogen-bonded mixtures with varying concentration are a complicated networked system that demands a detection technique with both time and frequency resolutions. Hydrogen-bonded pyridine–water mixtures are studied by a time-frequency resolved coherent Raman spectroscopic technique. Femtosecond broadband dual-pulse excitation and delayed picosecond probing provide sub-picosecond time resolution in the mixtures temporal evolution. For different pyridine concentrations in water, asymmetric blue versus red shifts (relative to pure pyridine spectral peaks) were observed by simultaneously recording both the coherent anti-Stokes and Stokes Raman spectra. Macroscopic coherence dephasing times for the perturbed pyridine ring modes were observed in ranges of 0.9–2.6 ps for both 18 and 10 cm − 1 10\hspace{0.33em}{{\rm{cm}}}^{-1} broad probe pulses. For high pyridine concentrations in water, an additional spectral broadening (or escalated dephasing) for a triangular ring vibrational mode was observed. This can be understood as a result of ultrafast collective emissions from coherently excited ensemble of pairs of pyridine molecules bound to water molecules.

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Pastorczak, Marcin, Michal Nejbauer, Tomasz Kardas i Czesiaw Radzewicz. "Femtosecond infrared pump – stimulated Raman probe spectroscopy: the method and its first application to study vibrational relaxation pathway in liquid water". EPJ Web of Conferences 205 (2019): 09026. http://dx.doi.org/10.1051/epjconf/201920509026.

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We apply femtosecond-infrared pump- stimulated Raman probe spectroscopy (fs-IR-SRS) which provides sub-100 fs time resolution, spectral resolution better than 10 cm-1 and the 100 cm-1 to 4000 cm-1 probe bandwidth to study vibrational relaxation pathway after vibrational excitation of OH stretching mode in HDO in the system composed of 30 % of HDO in D2O.

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Jeoung, Sae Chae, Hyo Soon Eom i Dongho Kim. "Transient Absorption and Raman Studies on Exciplex Formation Dynamics of Photoexcited Cu(II)(TMpy-P4) With Synthetic Polynucleotide". Laser Chemistry 19, nr 1-4 (1.01.1999): 299–303. http://dx.doi.org/10.1155/1999/52027.

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Exciplex formation dynamics of photoexcited copper(II) tetrakis (4-N-methylpyridyl) porphyrin (Cu(II)(TMpy-P4)) with added poly(dA-dT)2 and poly(dG-dC)2 has been investigated by using femtosecond transient absorption and nanosecond and picosecond transient Raman spectroscopic methods. It was observed that the decay time constant of the exciplex is strongly dependent on the polynucleotide and has a strong correlation with the appearance of new transient Raman bands.

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Kirkwood, Jason C., i A. C. Albrecht. "Multi-dimensional time-resolved coherent Raman six-wave mixing: a comparison of the direct and cascaded processes with femtosecond excitation and noisy light interferometry". Journal of Raman Spectroscopy 31, nr 1-2 (styczeń 2000): 107–24. http://dx.doi.org/10.1002/(sici)1097-4555(200001/02)31:1/2<107::aid-jrs493>3.0.co;2-e.

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Zhao Xiao-Hui, Ma Fei, Wu Yi-Shi, Ai Xi-Cheng i Zhang Jian-Ping. "Ultrafast internal conversion and vibrational relaxation in singlet excited-state all-trans-β-carotene as revealed by femtosecond time-resolved stimulated Raman spectroscopy". Acta Physica Sinica 57, nr 1 (2008): 298. http://dx.doi.org/10.7498/aps.57.298.

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Tran, H., P. Joubert, L. Bonamy, B. Lavorel, V. Renard, F. Chaussard, O. Faucher i B. Sinardet. "Femtosecond time resolved coherent anti-Stokes Raman spectroscopy: Experiment and modelization of speed memory effects on H2–N2 mixtures in the collision regime". Journal of Chemical Physics 122, nr 19 (15.05.2005): 194317. http://dx.doi.org/10.1063/1.1894020.

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