Picosecond time-resolved Raman spectroscopy

The first subsurface bone tissue Raman spectroscopic measurements were performed using picosecond time-resolved Raman spectroscopy on excised equine cortical bone [56, 57], In these experiments it was shown that a polystyrene backing could be detected through 0.3 mm of bone. The same picosecond technology was used to perform the first transcutaneous Raman spectroscopic measurements of bone tissue [58]. In this study, the cortical bone mineral/matrix ratios of excised limbs of wild type and transgenic (oim/oim) mice were compared and the differences demonstrated. 

Aramaki et al.30 examined the photochromic reactions of spirooxazines by picosecond time-resolved Raman spectroscopy. Vibrational resonance Raman spectra of the merocyanine isomer(s) recorded over a 50-ps-1.5-ns interval did not change. This indicated that the open ring opening to form a stable merocyanine isomer or the distribution of isomers31 was complete within 50 ps and that the isomer(s) distribution remained unchanged for at least 1.5 ns. 

Vibrational Cooling Process in Solution Probed by Picosecond Time-Resolved Raman Spectroscopy. Analysis of the Cooling Kinetics. 

Iwata, K. and Hamaguchi, H. (1994) Picosecond time-resolved Raman-spectroscopy of SI p-terphenyl and p-terphenyl-d]4 in solution - time-dependent changes of Raman band shapes. J. Raman Spectrosc., 25,... 

In picosecond time-resolved Raman spectroscopy, the sample is pumped and probed by energetically well-defined optical pulses, producing a full vibrational spectrum over a 1000 2000 cm 1 window.207 One would expect vibrational spectroscopy to be restricted to the picosecond time domain and above by the Heisenberg uncertainty principle (Equation 2.1), because a 1 ps transform-limited pulse has an energy width of... 

Iwata, K. Hamaguchi, H.-O., Microscopic mechanism of solute-solvent energy dissipation probed by picosecond time-resolved Raman spectroscopy. J. Phys. Chem. A 1997, 101, 632-637. 

Picosecond time-resolved Raman spectroscopy has been used to study the ultrafast relaxation dynamics of trows-stilbene cation radicals following two-photon ionization in acetonitrile [66]. The integrated Raman intensities due to the cation radicals rise in... 

Vibrational cooling rates in room temperature ionic liquids were measured with picosecond time-resolved Raman spectroscopy [63]. The 1570-cm Raman band of the first excited singlet (Sj) state of frans-stilbene was used. The recorded vibrational cooling rates in l-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (emimTf2N) and l-butyl-3-methylimidazolium bis(trifluoromethylsu]fonyl)imide (bmimTf2N) were close to those in ordinary molecular solvents despite a large difference in thermal diffusivity. 

Iwata, K., Yoshida, K., Takada, Y. and Hamaguchi, H., Vibrational cooling process of trans-stilbene in ionic liquids observed with picosecond time-resolved Raman spectroscopy, Chem. Lett. 36, 504-505 (2007). 

Everall N, Hahn T, Matuosek P, Parker A, Towrie M (2001) Picosecond time-resolved Raman spectroscopy of solids capabilities and limitations for fluorescence rejection and the influence of diffuse reflectance. Appl Spectrosc 55 1701-1708 Gaft M, Nagli L (2008) Laser-based spectroscopy for standoff detection of explosives. Opt Mater... 

When an electron is injected into a polar solvent such as water or alcohols, the electron is solvated and forms so-called the solvated electron. This solvated electron is considered the most basic anionic species in solutions and it has been extensively studied by variety of experimental and theoretical methods. Especially, the solvated electron in water (the hydrated electron) has been attracting much interest in wide fields because of its fundamental importance. It is well-known that the solvated electron in water exhibits a very broad absorption band peaked around 720 nm. This broad absorption is mainly attributed to the s- p transition of the electron in a solvent cavity. Recently, we measured picosecond time-resolved Raman scattering from water under the resonance condition with the s- p transition of the solvated electron, and found that strong transient Raman bands appeared in accordance with the generation of the solvated electron [1]. It was concluded that the observed transient Raman scattering was due to the water molecules that directly interact with the electron in the first solvation shell. Similar results were also obtained by a nanosecond Raman study [2]. This finding implies that we are now able to study the solvated electron by using vibrational spectroscopy. In this paper, we describe new information about the ultrafast dynamics of the solvated electron in water, which are obtained by time-resolved resonance Raman spectroscopy. 

S. Aramaki and G. H. Atkinson, Spirooxazine photochromism picosecond time-resolved Raman and absorption spectroscopy, Chem. Phys. Lett., 170, 181-186 (1990). 

The current detailed understanding of photo-induced electron transfer processes has been advanced dramatically by the development of modern spectroscopic methods. For example, the application of time-resolved optical spectroscopy has developed from modest beginnings (flash-phyotolysis with millisecond resolution) [108,109] to the current state of the art, where laser spectroscopy with nanosecond resolution [110-113] must be considered routine, and where picosecond [114-116] or even femtosecond resolution [117] is no longer uncommon. Other spectroscopic techniques that have been applied to the study of electron transfer processes include time-resolved Raman spectroscopy [118], (time resolved) electron spin... 

Time-resolved anti-Stokes Raman spectroscopy was used for monitoring vibrational relaxation dynamics in solution and provides information about specific modes in molecules under investigation [58, 59]. The experimental setup of a picosecond time-resolved Raman spectrometer is schematically shown in Figure 11.15 [59]. Probe-wavelength dependence of picosecond time-resolved anti-Stokes Raman spectra of a molecule under study allowed determination of... 

In the case of NOS 12, different kinetics were observed at 436 nm. In cyclohexane, there was a rapid rise, with a lifetime of 6.6 psec followed by a decay with a 100-psec lifetime. In 1-butanol, there was a rapid rise (lifetime=4.3 psec), a decay (43-psec lifetime), and a second longer decay within a 1.4-nsec lifetime. These findings were confirmed by picosecond time-resolved resonance Raman spectroscopy. In these Raman studies in cyclohexane, a single rate constant was observed, whereas in 1-butanol, three spectral components grew with different time constants. The data were said to be consistent with the photo-formation of two or three isomers trans about the central methine bond however, other transient species could be responsible for the observed kinetics because the absorption envelope obviously shifts and this would affect the resonance Raman bands. 

The metaiioporphyrins form a diverse class of molecules exhibiting complex and varied photochemistries. Until recently time-resolved absorption and fluorescence spectroscopies were the only methods used to study metailoporphyrln excited state relaxation in a submicrosecond regime. In this paper we present the first picosecond time-resolved resonance Raman spectra of excited state metaiioporphyrins outside of a protein matrix. The inherent molecular specificity of resonance Raman scattering provides for a direct probe of bond strengths, geometries, and ligation states of photoexcited metaiioporphyrins. 

The kinetics of the photochemical ring opening of cyclic dienes and trienes such as 1,3,5-cyclooctatriene (104) were determined by picosecond time-resolved UV resonance Raman spectroscopy (Ried et al., 1990) and provide excellent direct support for the Woodward-Hoffmann rules. 

Due to low, dark current and rapid readout characteristics, their large dynamic range (>18 bit for the CCD) and the two-dimensional array feature, the CCD and LCI-CCD are more versatile detectors. These detectors and the MCP-SPD array detector are particularly useful for picosecond, time-resolved emission, absorption, and Raman spectroscopy, and for imaging applications where signal averaging is required. 

Hashimoto H, Koyama Y, Ichimura K and Kobayashi T (1989) Time-resolved absorption spectroscopy of the triplet state produced from the all-trans, 1-cis, 9-cis, 13-cis, and 15-dv isomers of /3-caroteiie. Chem Phys Lett 162 517-522 Hashimoto H, Koyama Y, Hirata Y and MalagaN (1991) S and TI species of j3-car0tene generated by direct photoexcitation from the all-lrans, 9-cis, 13-ds, and 15-dv isomers as revealed by picosecond transient absorption and transient Raman spectroscopies. J Phys Chem 95 3072-3076 Hashimoto H, Miki Y, Kuki M, Shimamura T, Utsumi H and Koyama Y (1993) Isolation by high-pressure liquid chromatography of the cis-trans isomers of )3-apo-8 -carotenal. Determination of their So-state configurations by NMR spectroscopy and prediction of their S - and Ti-state configurations by transient Raman spectroscopy. J Am Chem Soc 115 9216-9225... 

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