Intense infrared

Quack M 1979 Master equations for photochemistry with intense infrared iight Ber. Bunsenges. Phys. Chem. 83 757-75... 

Quack M 1982 Reaction dynamics and statistical mechanics of the preparation of highly excited states by intense infrared radiation Adv. Chem. Rhys. 50 395-473... 

Infrared absorption properties of 2-aminothiazole were reported with those of 52 other thiazoles (113). N-Deuterated 2-aminothiazole and 2-amino-4-methylthiazo e were submitted to intensive infrared investigations. All the assignments were performed using gas-phase studies of the shape of the vibration-rotation bands, dichroism, isotopic substitution, and separation of frequencies related to H-bonded and free species (115). With its ten atoms, this compound has 24 fundamental vibrations 18 for the skeleton and 6 for NHo. For the skeleton (Cj symmetry) 13 in-plane vibrations of A symmetry (2v(- h, 26c-h- Irc-N- and 7o)r .cieu.J and... 

Benzoselenazoles have an additional band at 1590 to 1610 cm . The presence of high-intensity infrared bands in selenazolines is further evidence for the assignment of the selenazole F vibrations to ttc N (1650-1680 cm ) and the selenazole IF vibration to the group -N=C-... 

Carvone (Problem 12.39) has an intense infrared absorption at 1690 cm-1. What kind of ketone does carvone contain ... 

The catalyst precursor generally used for the reaction is rhodium dicarbonyl acetylacetonate. However, detailed infrared studies under the reaction conditions (ca. 1000 bar CO/H2 and 200°C) have shown both the [Rh(CO)4] and the [Rh12(CO)34 36]2 anions to be present in various concentrations at different stages of the reaction (62, 63). It is suggested that rhodium carbonyl clusters, characterized as having three intense infrared absorptions at 1868 10, 1838 10, and 1785 10 cm-1, are responsible for the catalysis (62), and it is believed that the reaction is dependent upon the existence of the following equilibria ... 

Figure 1. Testing the Keldish limit [1, 2] to ionization by intense infrared femtosecond/picosecond laser pulses used for control of chemical reactions [3, 4], (a) Electronic ground state embedded in a typical model potential curve with the ionization potential Es = 12.9 eV. (b) Intense ( o = 35.5 GV/m"1, Iq = 3.3 x 1014 W/cm2), ultra-short (tp = 0.5 ps), infrared (l/X = 3784 cm" ) laser pulse, (c) Expectation value for the position of the election, which is driven by the laser held shown in panel (b) [compare with ro = 122 A, Eq. (3)]. (d) Electron energy. These model calculations demonstrate that even very intense (/ > /Keldish) ultrashort 1R laser pulses may not cause ionization that is, the simple estimates (1)—<4) [1, 2] are not applicable.

Exercise 9-7 Which compound in each group would have the most intense infrared absorption band corresponding to stretching vibrations of the bonds indicated Give your reasoning. 

M. Yu Ivanov, D. R. Matusek, and J. S. Wright, Cbem. Pbys. Lett., 255,232 (1996). Altered Reaction Dynamics Lowered Barriers and Bound States Induced by Intense Infrared Laser Fields. 

Potassium hexafluoroplatinate(IV) may be identified by its x-ray powder diffraction pattern6 and infrared spectrum7 which in a Nujol mull has bands as follows 583(vs), 282(s), 259(ms) cm.-1. The crude product before recrystallization is sufficiently pure for most purposes but preparations carried out in quartz usually contain some potassium hexafluorosilicate, which may be detected by its very intense infrared absorptions at 741 and 483 cm.-1.8... 

The considerable electrical anisotropy of this salt is made still more evident on the room-temperature polarized infrared reflection spectra [30] (see also Chapter 6 and Fig. 1 of this chapter). In addition, these reflection spectra give a remarkably clear information on the existence of strong coupling between the quasi-one-dimensional electronic system and the symmetric ag vibrational modes of the TCNQ molecules. More precisely, under the effect of this coupling, these particular modes, which are normally Raman active but infrared nonactive, acquire an anomalous intense infrared activity together with an anomalous polarization [20,30,31]. 

Finally, charged excitations on the chain also generate new and intense infrared absorptions (IRAS lines) which are other manifestations of the strength of the electron-phonon coupling. 

Furthermore, it is possible to increase the sensitivity of the IR technique, and thus the probability of detecting transient surface species characterized by (very) low absorption coefficients (such as the intermediate species present during the first steps of the polymerization reaction on the Phillips catalyst) by exploiting the surface-enhanced infrared absorption (SEIRA) effect. It is known that molecules adsorbed on metal island films or particles exhibit 10-1000 times more intense infrared absorption than would be expected from conventional measurements without the metal (253-256). The possibility of performing SEIRA spectroscopy should therefore be expected to provide an opportunity to better investigate the nature of the intermediate species, not only for ethene polymerization on Cr(II)/ Si02, but for other reactions on solid catalysts. 

SIERA Surface-enhanced infrared absorption As in the case of surface-enhanced Raman scattering (SERS), molecules adsorbed on metal island films or particles exhibit intense infrared absorption several folds higher than what one would expect from conventional measurements without the metal. This effect is referred to as surface-enhanced infrared absorption (SEIRA). 

Figure 34.17. Watching a Single Motor Protein in Action. (A) An actin filament (blue) is placed above a heavy meromyosin (HMM) fragment (yellow) that projects from a bead on a glass slide. A bead attached to each end of the actin filament is held in an optical trap produced by a focused, intense infrared laser beam (orange). The position of these beads can be measured with nanometer precision. (B) Recording of the displacement of the actin filament induced by the addition of ATP. [After J. T. Finer, R. M. Simmons, and J. A. Spudich. Nature 368(1994) 113.]...

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