Time-resolved observation

Ruhman S, Joly A G and Nelson K A 1987 Time-resolved observations of coherent molecular vibrational motion and the general occurrence of impulsive stimulated scattering J. Chem. Phys. 86 6563-5... 

A similarly wide choice of lumophores can be found within photophysics and photochemistry.191 The excitation (or absorption) and emission bands of luminescence come in a variety of wavelength positions, intensities and shapes. Another parameter, which is gaining in popularity among designers, is the luminescence lifetime. Time-resolved observation is a neat way of dissecting out the response of the luminescent device from the emissive noise of real-life matrices. Photostability of lumophores is a parameter which perhaps deserves more attention as more and more demanding applications are being tackled. 

Baumann J. and Fayes M. D. (1986) Excitation Energy Transfer in Disordered Two-Dimensional and Anisotropic Three-Dimensional Systems Effects of Spatial Geometry on Time-Resolved Observables, J. Chem. Phys. 85, 4087-4107. 

In general, UXAS opens a new spectroscopic window for the direct ultrafast time-resolved observation of molecular motions during chemical reactions. (From Rose-Petruck, 2000)... 

The spectra of silver and gold nanoclusters are intense and distinct (Table 4). They are thus particularly suitable to detect the evolution of a cluster composition during the construction of a bimetallic cluster in mixed solution. The system studied by pulse radiolysis was the radiolytic reduction of a mixed solution of two monovalent ions, the cyano-silver and the cyano-gold ions Ag(CN)2 and Au(CN)2 (Fig- 7) [66]. Actually, the time-resolved observation demonstrated a two-step process. First, the atoms Ag and Au are readily formed after the pulse and coalesce into an alloyed oligomer. However, due to... 

Wu, F., and R. W. Carr, Time-Resolved Observation of the Formation of CF20 and CFCIO in the CF2C1 + 02 and CFCI2 + 02 Reactions. The Unimolecular Elimination of Cl Atoms from CF2CIO and CFCI20 Radicals, J. Phys. Chem., 96, 1743-1748 (1992). 

Bitea, C., Walther, C., Kim, J. I., Geckeis, H., Rabung, Th., Scherbaum, F. J. Cacuci, D. G. 2003a. Time-resolved observation of Zr02-colloid agglomeration. Colloids Surfaces A, 215, 55-66. 

In this section we report the first study of the micro-SQUID response of a low-spin molecular system, V15, to electromagnetic radiation. The advantages of our micro-SQUID technique in respect to pulsed electron paramagnetic resonance (EPR) techniques consist in the possibility to perform time-resolved experiments (below 1 ns) [59] on submicrometer sizes samples (about 1000 spins) [22] at low temperature (below 100 mK). Our first results on Vi5 open the way for time-resolved observations of quantum superposition of spin-up and spin-down states in SMMs. Other results obtained in similar systems but with large spins concern for example EPR measurements [10], resonant photon-assisted tunneling in a Feg SMM [60]. 

In laser measurements on hydrogen halides, the system under investigation is itself all, or part, of the active laser medium. Similar experiments have not yet been made on other molecules. However, in related experiments on CO, in the author s laboratory [242,432] and elsewhere [433], a CO cw laser has been used to probe the vibrational distributions in a reaction system outside the optical cavity that may act as an amplifier or absorber of lines from the laser. Time-resolved observations can be made for as long as one chooses after the reaction is initiated. If tunable infrared lasers become readily available this technique is likely to be applied more widely. 

The pulse radiolysis technique is a very powerful method for studying short-lived chemical species. Time-resolved observation gives access... 

Time-resolved Observation of Electron Transfer in Excited-state Reactions the Ba-FCHj case... 

Earlier studies on dye-sensitized Ti02 reported nanosecond time constants for the injection kinetics [16, 40-42]. These results were obtained indirectly from the measurement of the injection quantum yield and implicitly assumed that the interfacial electron transfer reaction was competing only with the decay of the dye excited state. Other studies were based on the same assumption but used measurements of the dye fluorescence lifetime, which provided picosecond-femtosecond time resolution [43-45]. Direct time-resolved observation of the buildup of the optical absorption due to the oxidized dye species S+ has been employed in more recent studies [46-51]. This appears to be a more reliable way of monitoring the charge injection process as it does not require any initial assumption on the sensitizing mechanism. 

Figure 7. Time-resolved observation of molecular vibrations in CH2Bt2 liquid recorded with a transient grating experimental arrangement using V-polarized pulses. The 5.2-THz oscillations correspond to oscillations of 173-cm bromine bending mode which was excited coherently through ISRS.

Onishi H, Iwasawa Y (1996) Dynamic visualization of a metal-oxide-surface/gas-phase reaction time-resolved observation by scanning tunneling microscopy at 800 K. Phys Rev Lett 76 791... 

S. Kurihara, T. Ikeda, T. Sasaki, H.-B. Kim, and S. Tazuke, Time-resolved observation of isothermal phase transition of liquid crystals triggered by photochemical reaction ofazobenzene dopant, Mol. Cryst. Liq. Cryst. 195, 251-263 (1991). 

T. Sasaki, T. Ikeda, and K. Ichimura, Time-resolved observation of photochemical phase transition in polymer liquid crystal, Macromolecules 25, 3807-3811 (1992). 

Figure 28.4 Time-resolved observation of the laser tsunami pushing a single polymer bead in solution and its model explanation.

Elsayed-Ali H. E., Norris T. B., Pessot M. A. and Mourou G. A. (1987), Time-resolved observation of electron-phonon relaxation in copper , Phys. Rev. Lett. 58, 1212-1215. 

The first picosecond time-resolved observations of a photosensitised charge-injection process in semiconductor particles were carried out by Moser et at. (1985). The rate of electron injection from the excited singlet state of the surface-adsorbed dye eosin, EO(Si), to the conduction band of colloidal Ti02 particles... 

Bitea, C. et al.. Time-resolved observation of ZrOj-colloid agglomeration. Colloids Surf. A, 215, 55,2003. 

The role of theory has been essential from concepmal as well as from a predictive point of view. Time-resolved observations are strongly dependent on the experimental conditions, such as laser wavelengths, duration of pulses and their shapes, competition between one- and many-photon processes, strength of the electric field, and so on. Here theory has the task not only to provide insight into the nature of time-dependent processes, but also to identify the conditions under which they can be experimentally observed [19-21, 44—55]. 

YAM 92] YAMANAKA T., KAWASAKI S., SHIBATA T., Time-resolved observations of solid reactions and structure transitions using a PSD, an SSD and computer aided measurement and control , X-ray Anal., vol. 35, p 415-423,1992. 

Clear-cut experimental evidence for the existence of an inverted region was provided in 1984 by the work Miller et al.352 on long-distance intramolecular electron transfer in the rigidly linked bichromophoric radical anions 9 (Figure 5.4), which were generated by pulsed electron injection. The electrons are initially captured with nearly equal probability by either the donor chromophore biphenyl or the acceptor chromophore mounted on the other side of the saturated 5a-androstane spacer. Electron transfer rates to attain equilibrium were determined by time-resolved observation of the ensuing absorbance changes. 

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