Knowledge Bank

The second overtone spectra of ArHF and $(HF)2$ are obtained by intracavity laser induced fluorescence with a Ti-sapphire ring laser and supersonic slit jet. Fundamental emission $(v=1)$ is monitored using a PbS detector. Sub-Doppler spectra of $(3000)-0,(3100)-0,(3110)-0$. and $(3210)-O$ transitions of ArHF are recorded. We determine vibrational band origins of $vo=11339.034,11412.438$ and $11422.378cm-1$ and rotational constants of $B=0.10330,0.10276,0.10118cm-1$ for the $(3000),(3100)$, and (3110) bands and $vO=11484.7$ for (3210). All fit extrapolations of related constants of HF stretching states $v=0-2$. Of the quartet $v=3(HF)2.(v1=3),(v2=3)$ and $(v1=2,v2=1)$ have been seen. Two subbands $K=0$ and $K=1$ are observed for $(v1=3)$, while only $K=0$ is seen for $(v2=3)$ and $(v1=2,V2=1)$. The Interconversion tunneling is quenched in all states. The band origins, rotational constants and predissociation line widths are $\begin{array}{lll} v_{O} = 11273.501cm^{-1}, & B= .22118 cm^{-1} \Delta= 100 MHz K=0, & \Delta= 1900 MHz K=1 (v_{1}=3); \ v_{O} = 11043.09 cm^{-1}, & B= .2240 cm^{-1} \Delta=104 MHz (v_{2}=3); \ v_{O} = 11552.8 cm^{-1}, & B= .221 cm^{-1}, & \Delta=1 MHz (v_{1}=2,v_{2}=1).\end{array} $ No discernable variation of predissociation width with J is found. The linewidths are different than expected from simply extending $v=1$ and 2 observations. The results for $(v1=3)K=0$ and $K=1$ can be understood in terms of specific centrifugal distortion interactions.