Laser photolysis of perfluoroalkyl iodides

Abstract

A full-field-view laser stroboscopic system that visualizes surface mode shapes in piezoelectric resonators has been developed. The system presented is based on stroboscopic laser irradiation, laser speckle, and two-dimensional correlation image processing. We employed a high-speed laser diode synchronized to the resonator motion to develop an in-plane vibrational distribution visualizer that is capable of operation above 10 MHz. The detection sensitivity of the proposed system is ten times better than that of previous laser speckle systems.

Dynamics of I*(2P1/2) production from fluorinated alkyl iodides at 266, 280, and ∼305 nm

“…The quantum yield of I* for other higher perfluoroalkyl iodides near the A-band maximum is usually found close to 1.0 and does not depend very much on the structure of the perfluoroalkyl radical in contrast to normal iodoalkanes as reported by earlier authors. [23][24][25][26][27][28][29][30][31] We also observe a similar effect from * measurements on the above iodides. From Table I, it is clear that the quantum yields of these iodides are very high at all the wavelengths employed by us.…”

“…We find * ͑0.89͒ is maximum for CF 3 I at 266 nm and falls off to 0.63 at ϳ305 nm. At 266 nm, Ershov 23 reported * as 0.91. However, more recent results of Felder, 35 Van Veen et al, 33 and Person et al 22 from time-of-flight experiments at 248 nm are in good agreement with our value of 0.89 for CF 3 I near the A band maximum.…”

“…Since then the dynamics of perfluoroalkyl iodides have been studied by several groups using a variety of techniques to monitor I* products. 15,[23][24][25][26][27][28][29][30][31][32][33][34] Recently the dissociation dynamics of CF 3 I and other fluorinated alkyl iodides has been studied by photofragment translational spectroscopy. 22,[35][36][37][38][39][40][41][42] Experimental I*/I branching ratios do not agree well with the relative contribution of the excited states as determined from MCD studies.…”

Secondary ion mass spectrometry of metal halides. 1. Stability of alkali iodide clusters

“…The largest observed n value for Nal and KI was Log-log plots of ion intensity vs. n (log In/I\ vs. log n) decrease linearly and are in agreement with previously published results. 5 The linearity of the logarithmic data is empirical in that no quantitative theory exists. However, the slope of the linear least-squares fit (i.e., B in log /" = A + B log n) is a relative measure of the extent and distribution of the alkali iodide cluster ions.…”

Potential energy surfaces for ground and excited electronic states of the CF3I molecule and their relevance to its A-band photodissociation

“…A prime example in this category is the CF 3 I molecule, which has 18 more valence electrons than un-substituted methyl iodide. It has been the subject of numerous experiments in which I* quantum yields have been obtained [5][6][7][8][9][10][11][12][13][14][15][16][17][18] and its absorption spectrum has also been measured. [19][20][21][22] Theoretical studies of CF 3 I are much rarer, but ab initio calculations have also been reported for this system, 23,24 as well as a treatment of its photodissociation dynamics.…”