Nanosecond time-resolved infrared

Yuzawa T, Kate C, George M W and Hamaguchi H O 1994 Nanosecond time-resolved infrared spectroscopy with a dispersive scanning spectrometer Appl. Spectrosc. 48 684-90... 

Nanosecond time resolved infrared (TRIR) spectroscopy has recently become available to physical organic chemists. This spectroscopy is an attractive tool for studying carbonyl nitrenes. Such work is in progress in several laboratories ... 

Microsecond to Nanosecond Time-Resolved Infrared Absorption Measurements... 

For microsecond to nanosecond time-resolved infrared absorption measurements, three types of spectroscopic methods have been developed (i) a method using an infrared laser, (ii) a method using a dispersive spectrometer, and (iii) a method using an FT-IR spectrometer. The time resolution of each of these is limited to the fastest time-response capability of the detector used. 

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... 

Direct observation of singlet (alkyl)carbenes usually requires matrix isolation conditions. " Using the 7i-donor and a-attractor methoxy substituent, Moss and co-workers could characterize the (methoxy)(methyl)carbene (MeOCMe) by ultraviolet (UV) and infrared (IR) spectroscopies, but only in a nitrogen matrix (at 10 K) or in solution thanks to a nanosecond time-resolved LFP technique (fi/2 < 2ps at 20 °C). The remarkable stability of carbene XlVa both in the solid state and in solution (no degradation observed after several weeks at room temperature), prompted us to investigate the preparation of (phosphino)(alkyl)carbenes. 

Time-resolved Infrared spectroscopy (TRIR), a combination of UV flash photolysis and fast IR spectroscopy (ns), has been outstandingly successful in identifying reactive intermediates [5] and excited states [6] of metal carbonyl complexes in solution at room temperature. We have used infrared spectroscopy to probe the mechanism of photo-17] and electrochemical [8] catalytic reduction of COj. We have used TRIR to study organometallic reactions in supercritical fluids on a nanosecond time-scale [9-10]. 

The detection of short-lived transient species is often achieved by flash photolysis where an extremely short flash of UV/Vis radiation from a laser generates a high concentration of transient species, and a second probe beam monitors any changes that occur after the flash. Traditionally, UVA is spectroscopy has been used as a detection method. However, time-resolved infrared spectroscopy (TRIR), a combination of UV flash photolysis and fast IR detection, also has a long history. There are several different approaches to fast IR spectroscopy and the method of choice depends upon the timescale of the reaction. Measurements on the nanosecond to millisecond timescale are obtained using point-by-point techniques or by step-scan FTIR. In the point-by-point approach, a continuous wave IR laser (GO or diode) or globar is used as the IR source, which is tuned to one particular IR frequency (Figure 3). ... 

G. L. Carr, High-resolution microspectroscopy and sub-nanosecond time-resolved spectroscopy with the synchrotron infrared source, Vib. Spec-... 

In this chapter, millisecond time-resolved infrared measurements are first described in Section 20.2 for this time scale, time resolution is set by the time needed to measure (scan) a spectrum. Then, microsecond to nanosecond time-resolved measurements, which are limited by the detector response time are described in Section 20.3, and finally, picosecond to femtosecond time-resolved measurements, the time resolution for which is determined by the width of the laser pulse used for the measurement, are described in Section 20.4. 

Many photochemical and photophysical phenomena occur on a time scale shorter than a nanosecond. In order to follow such fast phenomena by infrared spectroscopy, picosecond to femtosecond time-resolved infrared measurements are required. Since time resolving in this time range cannot be performed by utilizing the fast-response capability of a detector and the time-resolving power of an electronic circuit (gate circuit, etc.), the following optical methods are mainly used (i) a method based on the upconversion (optical gating) process, and (ii) a method which detects pulsed infrared radiation itself. At present, the latter method is commonly used for picosecond to femtosecond time-resolved measurements. 

In 2005, Towrie et al. [30] developed another time-resolved infrared spectrometer capable of performing femtosecond to microsecond time-resolution measurements, by adding to their spectrometer described in Ref [29] a sub-nanosecond Q-switch Nd YV04 laser (wavelength 1064 nm, pulse width 0.6 ns). The pulses generated by this laser were electronically synchronized with the probe pulses with about 0.3 ns jitter, and the harmonics of pulses from this laser were used as the pump pulses. 

PMTs have a relatively large detection area making them well suited to most monochromators. Their dark noise per unit detection area is the lowest of any detector (lower than even cryogenically cooled CCDs). Their quantum efficiencies are in the range of 1-40% in the ultraviolet and visible spectral regions, but fall off rapidly in the near-infrared. PMTs have nanosecond response times that are useful for time-resolved Raman measurements. 

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