Absorption spectra in the vacuum ultraviolet region of small molecules in condensed phases

With radiation from a synchrotron we measured the spectra of several small molecular species, in the solid phase at 10 K, either pure – O2, NO, CO2, N2O, H2O and NH3 – or, for NH3, also dispersed in Ar at molar ratio 1/250, from the onset of absorption in the ultraviolet region until the limits of transmission by crystalline LiF or solid Ar. In a quantitative treatment of spectral data, we fitted the total absorption profile divided by wavenumber to Gaussian curves of minimal number, and made tentative assignments of electronic transitions and vibrational structure by comparison with spectra of gaseous species. These results illuminate the nature of electronic spectra of samples in solid phases in the vacuum ultraviolet region.