Knowledge Bank

The rovibrational spectrum of several $\Sigma \leftarrow \Sigma$ and $\Pi \leftarrow \Sigma$ type bands of $Ar-NH3$ complex formed in a slit-jet supersonic expansion has been observed over the $v2$ fundamental region of $NH3$ with a tunable diode laser. The complicated spectrum due to the inversion and nearly free internal rotation of the $NH3$ unit has been assigned based on a previous $work1$, which shows that the upper and lower states of the observed transitions are correlated to $NH3(j=0,1,2;k\prime =0,1)$ and $NH3(j\prime \prime =0,1;k\prime \prime =0,1)$ states respectively. By using a rotational-internal-rotational-inversion Hamiltonian for spectral analysis, spectroscopic constants related to these bands have been determined and the vibrational dependence to the Legendre coefficients has been evaluated, leading to accurate characterization of the intermolecular potential surface for the excited vibrational state.