Cryoemission of Nitrous Oxide and Ethanol: Dynamic and Energy Characteristics

Abstract

We studied dynamic and spectral characteristics of light emission produced during cryodeposition of nitrous oxide and ethanol onto metal substrates at a temperature of 10 K and a pressure of a gas phase of $10^{-2}$ Torr. It was established that this radiation is comprised of a large number of individual flashes of varying amplitude, wavelength and duration. Our measurements indicated that for nitrous oxide the rise time required to reach the maximum intensity of a single flash is $0.015 \times 10^{-3}$ s, whereas for ethanol such time is $0.3\times 10^{-3}$ s (i.e., 20 times greater). We attribute such discrepancy to the significant difference between the intrinsic molecular dipole moments of nitrous oxide $(\mu = 0.097\,D)$ and ethanol $(\mu = 1.68\,D)$. Emission spectra of both nitrous oxide and ethanol were measured in the wavelength range of 350–1050 nm. They consist of discrete peaks located at 517, 562, 690, 726, 805 and 866 nm for nitrous oxide and 387, 392, 822, 995 and 1019 nm for ethanol. To explain the obtained results, we consider two models based on the assumptions of existence of isomeric states of the nitrous oxide molecules, as well as of processes of molecular dipole ordering/disordering during cryodeposition from the gas phase.