NASA Logo, External Link
Facebook icon, External Link to NASA STI page on Facebook Twitter icon, External Link to NASA STI on Twitter YouTube icon, External Link to NASA STI Channel on YouTube RSS icon, External Link to New NASA STI RSS Feed AddThis share icon
 

Record Details

Record 1 of 8928
Single photon infrared emission spectroscopy: a study of IR emission from UV laser excited PAHs between 3 and 15 micrometers
External Online Source: doi:10.1021/jp9724434
Author and Affiliation:
Cook, D. J.(University of California, Department of Chemistry, Berkeley 94720-1460, United States)
Schlemmer, S.
Balucani, N.
Wagner, D. R.
Harrison, J. A.
Steiner, B.
Saykally, R. J.
Abstract: Single-photon infrared emission spectroscopy (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs). A supersonic free-jet expansion has been used to provide emission spectra of rotationally cold and vibrationally excited naphthalene and benzene. Under these conditions, the observed width of the 3.3-micrometers (C-H stretch) band resembles the bandwidths observed in experiments in which emission is observed from naphthalene with higher rotational energy. To obtain complete coverage of IR wavelengths relevant to the unidentified infrared bands (UIRs), UV laser-induced desorption was used to generate gas-phase highly excited PAHs. Lorentzian band shapes were convoluted with the monochromator-slit function in order to determine the widths of PAH emission bands under astrophysically relevant conditions. Bandwidths were also extracted from bands consisting of multiple normal modes blended together. These parameters are grouped according to the functional groups mostly involved in the vibration, and mean bandwidths are obtained. These bandwidths are larger than the widths of the corresponding UIR bands. However, when the comparison is limited to the largest PAHs studied, the bandwidths are slightly smaller than the corresponding UIR bands. These parameters can be used to model emission spectra from PAH cations and cations of larger PAHs, which are better candidate carriers of the UIRs.
Publication Date: Feb 26, 1998
Document ID:
20040088946
(Acquired Sep 07, 2004)
Subject Category: EXOBIOLOGY
Document Type: Journal Article
Publication Information: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment & general theory; p. 1465-81; (ISSN 1089-5639); Volume 102; 9
Publisher Information: United States
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: BENZENE; CYCLIC HYDROCARBONS; INFRARED LASERS; INFRARED RADIATION; INFRARED SPECTROPHOTOMETERS; LASERS; NAPHTHALENE; PHOTONS; SPECTROPHOTOMETRY; ULTRAVIOLET LASERS; ARGON; ASTRONOMY; COSMIC DUST; EXOBIOLOGY; EXTRATERRESTRIAL ENVIRONMENTS; TEMPERATURE; ULTRAVIOLET RADIATION; ULTRAVIOLET SPECTROSCOPY
Other Descriptors: BENZENE/ANALYSIS/CHEMISTRY/RADIATION EFFECTS; LASERS; NAPHTHALENES/ANALYSIS/CHEMISTRY/RADIATION EFFECTS; PHOTONS; POLYCYCLIC HYDROCARBONS/ANALYSIS/CHEMISTRY/RADIATION EFFECTS; SPECTROPHOTOMETRY, INFRARED/INSTRUMENTATION/METHODS; ARGON; ASTRONOMY; COMPARATIVE STUDY; COSMIC DUST; EXTRATERRESTRIAL ENVIRONMENT; SPECTROPHOTOMETRY, ULTRAVIOLET; SUPPORT, NON-U.S. GOV'T; SUPPORT, U.S. GOV'T, NON-P.H.S; TEMPERATURE; ULTRAVIOLET RAYS; NASA DISCIPLINE EXOBIOLOGY; NON-NASA CENTER
Availability Source: Other Sources
› Back to Top
NASA Logo, External Link
NASA Official: Gerald Steeman
Site Curator: STI Program
Last Modified: August 23, 2011
Contact Us