Dimer Formation of H_2 with Ar at Liquid Nitrogen Temperature; Red shadings of the (0,0) and (1,0) Lyman Bands

The absorption spectrum of the (0,0) and (1,0) Lyman bands of H_2 were investigated in the Argon matrix at liquid nitrogen temperature. Red shadings of the R(0), R(1) and P(1) lines were observed. There is theoretical calculation of LeRoy-Hutson intermolecular potential for the H_2-Ar dimer [J. Chem. Phys. 86:837-853, 1987]. The potential depth of the drmer D_e is 51.069cm^ with about 30cm^ zero point energy; the energy D_0=21cm^ corresponds to the energy below the bound free state. The 21cm^ (14 oK) is fairly lower than 78 oK (54cm^) of liquid nitrogen temperature. However, the population of the ground state of the dimer mostly should be mostly populated in the potential well of the dimer. The shading of H_2 lines to the long wavelength side indicates that the upper levels of the dimer have deeper potential well than that of the lower level in the dimer complex. The fact suggests that the upper state of the complex, H_2^*(2pσB ^1Σ^+_u)+Ar(3p^S) may have the potential well with deeper depth than 50cm^ it is estimated to be D_e=91～166cm^ and D_0=61～136cm^