VUV Linewidths and Band Oscillator Strengths
N VUV Linewidths and Band Oscillator Strengths
G. Stark (Physics Department, Wellesley College), P.L. Smith (CURSOAR Technologies and CfA)
Analyses of Voyager EUV occultation measurements of the N -rich
atmospheres of Titan and Triton have been hampered by the lack of
fundamental spectroscopic data for N -- in particular, by the lack
of reliable f-values and linewidths for electronic bands of N
in the 800 to 1000 Å wavelength region.
In order to address this shortfall, we have studied
the photoabsorption spectrum of N with a resolving power
( 
) of 90,000
to 170,000. New band-integrated photoabsorption cross sections
(i.e., f-values) for the region 900 and 950 Å\
will be presented. Data for linewidths -- which, in the case of the
EUV bands
of N , are often determined by predissociation lifetimes rather than
by Doppler effects -- are as essential as
f-values in calculations of the transmission of radiation through the
high column densities of N (nl 
10 
cm 
) observed by the Voyager spacecraft
at Titan and Triton. We will present preliminary
linewidth results for some b(v 
)-X(0)
bands of N . We will also
demonstrate that, for some bands and for high column densities,
isotopically rare 
N 
N may contribute disproportionately
to N absorption. This work supported in part by NASA Grants
and NAGW-3607 and -5200.