Nanosecond Time-Resolved Resonance

Varotsis C and Babcock G T 1993 Nanosecond time-resolved resonance Raman spectroscopy/Mef/rods Enzymol. 226 409-31... 

The photophysical properties of [Ru(TBP)(CO)(EtOH)], [Ru(TBP)(pyz)2], [Ru(TBP)(pyz)] (Fl2TBP = 5,10,15,20-tetra(3,5-tert-butyl-4-hydroxyphenyl)porphyrin) have been investigated by steady-state and time-resolved absorption and emission spectroscopies. The complexes are weakly luminescent, and the origins of this behavior is discussed.Transient Raman spectroscopic data have been reported for [Ru(TPP)(py)2], [Ru(TPP)(CO)(py), and [Ru(TPP)(pip)2] (pip = piperidine),and nanosecond time-resolved resonance Raman spectroscopy has been used to examine the CT excited states of [Ru(0EP)(py)2] and [Ru(TPP)(py)2]. " ... 

Probing Metalloproteins Electronic absorption spectroscopy of copper proteins, 226, 1 electronic absorption spectroscopy of nonheme iron proteins, 226, 33 cobalt as probe and label of proteins, 226, 52 biochemical and spectroscopic probes of mercury(ii) coordination environments in proteins, 226, 71 low-temperature optical spectroscopy metalloprotein structure and dynamics, 226, 97 nanosecond transient absorption spectroscopy, 226, 119 nanosecond time-resolved absorption and polarization dichroism spectroscopies, 226, 147 real-time spectroscopic techniques for probing conformational dynamics of heme proteins, 226, 177 variable-temperature magnetic circular dichroism, 226, 199 linear dichroism, 226, 232 infrared spectroscopy, 226, 259 Fourier transform infrared spectroscopy, 226, 289 infrared circular dichroism, 226, 306 Raman and resonance Raman spectroscopy, 226, 319 protein structure from ultraviolet resonance Raman spectroscopy, 226, 374 single-crystal micro-Raman spectroscopy, 226, 397 nanosecond time-resolved resonance Raman spectroscopy, 226, 409 techniques for obtaining resonance Raman spectra of metalloproteins, 226, 431 Raman optical activity, 226, 470 surface-enhanced resonance Raman scattering, 226, 482 luminescence... 

Ma, C., Du, Y., Kwok, W.M. and Phillips, D.L. (2007) Femtosecond transient absorption and nanosecond time-resolved resonance Raman study of the solvent-dependent photo-deprotection reaction of... 

Nanosecond time-resolved resonance Raman and absorption spectra of 6-nitroBIPS in deoxygenated cyclohexane were obtained in the 20-100-ns time region, extending an earlier study169 in the 200-2000-ns time region. A sequence of three transients was observed (1) the lowest triplet state 7i, X 435 nm, of the spiro form (2) the open merocyanine form, X 580 nm, formed from the triplet (1) and (3) a dimer of the merocyanine, X 540 nm.170... 

Sakai, M., Mizuno, M. and Takahashi, H. (1998) Picosecond-nanosecond time-resolved resonance Raman study of... 

The photophysics and photochemical reactions of 2-(l-hydro3yethyl)-9,10-anthraquinone have been studied by a combination of femtosecond transient absorption, nanosecond transient absorption and nanosecond time-resolved resonance Raman spectroscopy techniques, as well as DFT calculations. In acetonitrile, intersystem crossing to the triplet excited state is the predominating process. In isopropanol, photoreduction to a ketyl radical intermediate is observed. In neutral or moderately acidic aqueous solutions, a photoredox reaction occurs after initial protonation of the carbonyl ojqrgen, while under stronger acidic conditions photohydration takes over. ... 

Since there are a large number of different experimental laser and detection systems that can be used for time-resolved resonance Raman experiments, we shall only focus our attention here on two common types of methods that are typically used to investigate chemical reactions. We shall first describe typical nanosecond TR spectroscopy instrumentation that can obtain spectra of intermediates from several nanoseconds to millisecond time scales by employing electronic control of the pnmp and probe laser systems to vary the time-delay between the pnmp and probe pnlses. We then describe typical ultrafast TR spectroscopy instrumentation that can be used to examine intermediates from the picosecond to several nanosecond time scales by controlling the optical path length difference between the pump and probe laser pulses. In some reaction systems, it is useful to utilize both types of laser systems to study the chemical reaction and intermediates of interest from the picosecond to the microsecond or millisecond time-scales. 

The first laser Raman spectra were inherently time-resolved (although no dynamical processes were actually studied) by virtue of the pulsed excitation source (ruby laser) and the simultaneous detection of all Raman frequencies by photographic spectroscopy. The advent of the scanning double monochromator, while a great advance for c.w. spectroscopy, spelled the temporary end of time resolution in Raman spectroscopy. The time-resolved techniques began to be revitalized in 1968 when Bridoux and Delhaye (16) adapted television detectors (analogous to, but faster, more convenient, and more sensitive than, photographic film) to Raman spectroscopy. The advent of the resonance Raman effect provided the sensitivity required to detect the Raman spectra of intrinsically dilute, short-lived chemical species. The development of time-resolved resonance Raman (TR ) techniques (17) in our laboratories and by others (18) has led to the routine TR observation of nanosecond-lived transients (19) and isolated observations of picosecond-timescale events by TR (20-22). A specific example of a TR study will be discussed in a later section. 

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. 

The use of picosecond pulses to minimize the Interference of fluorescence with the Raman spectrum was also demonstrated (5) at about that time. The use of vldicon detection in Raman spectroscopy was demonstrated (6) in 1976. The first resonance Raman spectrum taken for a photobiologlcal system (bacteriorhodopsin) in the nanosecond time scale was (7) in 1977. The resonance Raman spectra of bacteriorhodopsin have also been measured in the microsecond (8,9,10) and in the millisecond (11) time domain. Recently the time resolved resonance Raman spectra of photolyzed hemoglobin derivatives have been reported (12). 

CLM method can also be combined with various kinds of spectroscopic methods. Fluorescence lifetime of an interfacially adsorbed zinc-tetra-phenylporphyrin complex was observed by a nanosecond time-resolved laser induced fluorescence method [25]. Microscopic resonance Raman spectrometry was also combined with the CLM. This combination was highly advantageous to measure the concentration profile at the interface and a bulk phase [14]. Furthermore, circular dichroic spectra of the liquid-liquid interface in the CLM could be measured [19]. 

Nanosecond pump probc time-resolved resonance Raman experiments were carried out with two Nd YAG lasers (At=7 ns) which provide the pump- (532 nm, 4 mJ) and probe pulses (416 nm, 100 mJ), a triple polychromator equipped with an intensified photodiode array, and a slow spinning cell (25tpm). For every sample, spectra were taken for delay times of At=-20, 0, 20,100 and 500 ns, 1,10,100 and 500 is, and 1ms. ... 

As already noted, Schneider and co-workers were the first to report nanosecond time-resolved Raman spectra of spirooxazine derivatives (including the spironaphthoxazine), using resonance CARS.18 Two years later, the same group... 

Surface Raman techniques have been used in applications such as in situ ink analysis (cfr also Chps. 1.2.3.1.1-2). Nanosecond laser flash photolysis and time-resolved resonance Raman spectroscopy have been used to study reactions between the AOs a-tocopherol and ascorbate and the triplet excited states of duroquinone (DQ) and ubiquinone (UQ). 

The picosecond pulsed (pp), nanosecond pulsed (np), and cw experiments all seek to obtain RR spectra which accurately reflect the vibrational degrees of freedom assignable to the neutral, ground-states of Bchl (P and accessory) and Bpheo prior to photo-excitation and charge separation. These spectra are important elements in the analysis of time-resolved Raman spectra (e.g., picosecond time-resolved resonance Raman, PTR, experiments) on transient species for two reasons ... 

The conditions which determine whether flash photolysis can be used to smdy a given chemical system are (i) a precursor of the species of kinetic interest has to absorb light (normally from a pulsed laser) (ii) this species is produced on a timescale that is short relative to its lifetime in the system. Current technical developments make it easy to study timescales of nanoseconds for production and analysis of species, and the use of instrumentation with time resolution of picoseconds is already fairly common. In certain specific cases, as we will see in the last part of this chapter, it is possible to study processes on timescales greater than a few femtoseconds. Once the species of interest has been produced, it is necessary to use an appropriate rapid detection method. The most common technique involves transient optical absorption spectroscopy. In addition, luminescence has been frequently used to detect transients, and other methods such as time-resolved resonance Raman spectroscopy and electrical conductivity have provided valuable information in certain cases. 

Bisby, R. and Parker, A. W. (1995) Reactions of excited triplet duroquinone with alpha-tocopherol and ascorbate a nanosecond laser flash photolysis and time-resolved resonance Raman investigation. J. Am. Chem. Soc., 117, 5664-5664. 

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