Mode selectivity

Weinacht T C, White J L and Bucksbaum P H 1999 Toward strong field mode-selective chemistry J. Phys. Chem. A 103 10 166-8... 

Modem photochemistry (IR, UV or VIS) is induced by coherent or incoherent radiative excitation processes [4, 5, 6 and 7]. The first step within a photochemical process is of course a preparation step within our conceptual framework, in which time-dependent states are generated that possibly show IVR. In an ideal scenario, energy from a laser would be deposited in a spatially localized, large amplitude vibrational motion of the reacting molecular system, which would then possibly lead to the cleavage of selected chemical bonds. This is basically the central idea behind the concepts for a mode selective chemistry , introduced in the late 1970s [127], and has continuously received much attention [10, 117. 122. 128. 129. 130. 131. 132. 133. 134... 

Wyatt R E, Hose G and Taylor H S 1983 Mode-selective multiphoton excitation in a model system Phys. Rev. A 28 815-28... 

Fehrensen B, Luckhaus D and Quack M 1999 Mode selective stereomutation tunnelling in hydrogen peroxide isotopomers Chem. Phys. Lett. 300 312-20... 

Quack M and Sutcliffe E 1984 The possibility of mode-selective IR-multiphoton excitation of ozone Chem. Phys. Lett. 105 147-52... 

Quack M 1991 Mode selective vibrational redistribution and unimolecular reactions during and after IR-laser excitation Mode Selective Chemistry ed J Jortner, R D Levine and B Pullman (Dordrecht Kluwer) pp 47-65... 

B2.5.5.4 LASER ISOTOPE SEPARATION AND MODE-SELECTIVE REACTIONS... 

Figure B2.5.18 compares this inter molecular selectivity with intra molecular or mode selectivity. In an IR plus UV, two-photon process, it is possible to break either of the two bonds selectively in the same ITOD molecule. Depending on whether the OFI or the OD stretching vibration is excited, the products are either IT -t OD or FIO + D [24]- hr large molecules, mirmnolecular selectivity competes with fast miramolecular (i.e. unimolecular) vibrational energy redistribution (IVR) processes, which destroy the selectivity. In laser experiments with D-difluorobutane [82], it was estimated that, in spite of frequency selective excitation of the...

Related results of promotion (catalysis) and inliibition of stereonuitation by vibrational excitation have also been obtained for the much larger molecule, aniline-NHD (CgH NHD), which shows short-time chirality and stereonuitation [104. 105]. This kind of study opens the way to a new look at kinetics, which shows coherent and mode-selective dynamics, even in the absence of coherent external fields. The possibility of enforcing coherent dynamics by fields ( coherent control ) is discussed in chapter A3.13. 

Wheeler M D, Anderson D T, Todd M W, Lester M I, Krause O J and Clary D C 1999 Mode-selective decay dynamics of the ortho-Hj-OH complex experiment and theory Mol. Phys. 97 151-8... 

Operating Mode Selection Process Variable SelectionJ... 

Therefore, in order to obtain a 1,4-addition of an allyl residue to an enone, two activation modes can be used reactions take place either under electrophilic conditions with Lewis acid promotion, or in the presence of fluoride ions. This is important as the stereochemical outcome often depends on the activation mode selected. 

Data acquisition Scan mode Selected-ion-monitoring mode Erratic component quantitation Reproducible component quantitation... 

HOMO Amplitudes, Quasi-Intermediate Structures, and Mode Selectivities... 

The lone pairs on the nitrogen and oxygen atoms make a significant difference in the chemical reactions (Scheme 17). P-Arylenamines undergo [2-t-2] cycloaddition reactions [93] whereas P-arylenol ethers undergo [2h-2h-2] cycloaddition reactions [94]. The mode selectivity was attributed [95] to the HOMO amplitude or the n bond polarity. 

Scheme 19a,b Nonbonded attraction controls the regioselectivity (a) and the mode selectivity (b)... 

Figure 14. Mode selectivity in photodissociation of V (OCO). The ratio of the reactive (VO + CO) to nonreactive (V + CO2) product is measured at the peaks of the vibronic bands labeled in Fig. 13. The data below 16,600 cm is from bands accessed by one-photon excitation data at higher energy was obtained by vibrationally mediated photodissociation exciting the OCO antisymmetric stretch.

Watanabe, K., Takagi, N. and Matsumoto, Y. (2005) Mode-selective excitation... 

Fig. 11 Mode-selective ESPT in 2-(2 -Pyridyl)pyrrole indicates that the ESIPT reaction is associated with in-plane vibration modes (reprint from ref. [97], Copyright 2005 American Chemical Society)...

Kijak M, Nosenko Y, Singh A et al (2007) Mode-selective excited-state proton transfer in 2-(2 -pyridyl)pyrazole isolated in a supersonic jet. J Am Chem Soc 129 2738-2739... 

Mode selection buttons. Located directly under each mode indicating light, each button will select its respective mode of control. If the button below the "M" mode light is depressed, the controller will be in the manual mode of operation if the button below the "A" mode light is depressed, the controller will be in the automatic mode of operation. 

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