Ultraviolet absorption spectrum of nitrous oxide as a function of temperature and isotopic substitution

Publisher Website
Google Scholar
Abstract
The ultraviolet absorption spectra of nitrous oxide and its 15N isotopes over the wavelength range 197 to 172 nm and between 150 and 500 K show a weak continuous absorption and a pattern of diffuse banding that became pronounced at higher temperatures. The temperature dependence of the absorption spectrum results from the activation of the n″2 bending mode. Deconvolution of the data shows that absorption by molecules in the (010) vibrational mode results in a spectrum of vibrational bands superimposed on a continuum. A weaker and nearly continuous spectrum results from the ultraviolet absorption by molecules in the (000) vibrational mode. Analysis of the structuring indicates n′2 = (490±10) cm−1. No rotational structure can be observed. Measurement of the n′2 isotope shift is used to identify the quantum number of the upper state vibrational levels. Normal coordinate anaylsis of the excited state is used to determine a self-consistent set of molecular parameters: bond angle (115°), the values of n′1 and n′3 (1372 and 1761 cm−1, respectively), and the force constants of the upper state. It is suggested that the transitions observed are 1S−(1A′′)←X~¯ 1S+ and 1D←X̃ 1S+.

This publication has 31 references indexed in Scilit: