Vibrational relaxation of highly excited NCNO in collisions with He, Ar and N2
Abstract
The
relaxation of vibrationally highly excited NCNO has been studied using the technique of time-resolved
infrared fluorescence (TR-IRF). A pulsed dye laser operating at 600 nm, or in some experiments at 640 nm, excited
NCNO to its S1
state whence radiationless transitions transfer the molecules to high vibrational levels
of the S0 ground state below the dissociation limit. IRF was observed at ca. 4.6 μm, corresponding to
fundamentals in the CN stretching vibration of NCNO. Values of
ΔE
, the mean energy removed per collision
with the diluent gas (Ar, N2 or He) were derived as a function of
E
, the mean internal energy content
of the excited molecules. The variation of
ΔE
with
E
was approximately
linear and, at
E
= 10000 cm−1,
ΔE
= 0.44 ± 0.03 cm−1 for
Ar,
ΔE
= 0.62 ± 0.04
cm−1 for N2 and
ΔE
= 0.57 ± 0.04 cm−1 for He.