Vibrational overtone spectra of styrene (liquid) and polystyrene (solid~ studied by the laser-induced thermal lens (for AV = 6) and the conventional near infrared absorption (for AV = 3-5) techniques. are reported. For polystyrene, the overt()ne energy• bond length correlation predicts that the aryl CH bonds are-0-0005 A longer than that in benzene, while no such conclusions could be drawn on styrene. The sp] CH overtones in polystyrene are observed on the low energy side of the aryl CH overtones.
Even though there is great practical benefit from evidence that ideal theories are reasonable approximations at small separations (10-30 A) where these relations are expected to fail, we should not be lulled into complacency. Why do not we observe major deviations from ideality due to structure of the solvent, finite ion size, correlations, and fluctuations? What is the origin(s) of the short-range repulsion and its decay at large separations? Furthermore, does the exponential form for the close-range repulsion hold at very close proximity? The power-law attraction should overwhelm the repulsion to cause a precipitous collapse. Clearly, stiff-steric interactions must exist which are of ultimate importance ARTICLES in lamellar phase instability and bilayer coalescence at extreme dehydration. Vibrational overtone spectra of acetophenone and benzaldehyde in the visible and near-infrared regions are studied by the dual beam thermal lens and the conventional near-infrared absorption techniques. The observed increase in the mechanical frequency of the aryl CH bond from that of benzene is attributed to the decrease in the aryl CH bond length caused by the electron-withdrawing property of the substituents. Overtone spectra also demonstrate that acetophenone contains two types of methyl CH bonds arising from the anisotropic environments created by oxygen lone pair and carbonyl P electrons. The local-mode parameters of the two types of CH bonds are compared with those of acetone and acetaldehyde. The possible factors influencing the methyl CH bonds in acetophenone are discussed.
Acknowledgment. This work was supported by the Medical
CH Overtones in Acetophenone and
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.