Laboratory studies of 3.3 micron emission from naphthalene induced by 193 and 248 nanometer excitation

Abstract

view Abstract Citations (41) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Laboratory Studies of 3.3 Micron Emission from Naphthalene Induced by 193 and 248 Nanometer Excitation Williams, Richard M. ; Leone, Stephen R. Abstract Laboratory studies of infrared emission from gas-phase naphthalene in the 3.3 micrometer region following ultraviolet laser excitation are used to interpret the unidentified infrared bands observed in many astronomical objects. A time-resolved Fourier transform infrared emission technique acquires the time and spectrally resolved data. Two excitation wavelengths are employed: 193 nm and 248 nm. The infrared emission features are strongly dependent on the initial excitation energy. Wavelength-resolved spectra recorded 6.8 microseconds after the laser pulse show a 45/cm redshift from the gas-phase absorption spectra for 193 nm excitation and 25/cm for 248 nm excitation. We hypothesize that a series of sequence bands originating from the highly vibrationally excited ensemble of molecules is responsible for the observed shift. As collisional and radiative deactivation removes energy from the highly vibrationally excited molecules, the maximum in the emission profile gradually approaches the customary absorption maximum. This indicates that the amount of redshift is strongly dependent on the amount of internal vibrational energy in the molecule at the time of the vibrational transition. Publication: The Astrophysical Journal Pub Date: April 1995 DOI: 10.1086/175559 Bibcode: 1995ApJ...443..675W Keywords: Infrared Spectra; Interstellar Matter; Laser Induced Fluorescence; Molecular Excitation; Naphthalene; Red Shift; Ultraviolet Lasers; Vibrational States; Fourier Transformation; Molecular Collisions; Radiative Transfer; Astrophysics; INFRARED: ISM: LINES AND BANDS; LINE: IDENTIFICATION; MOLECULAR PROCESSES full text sources ADS |