Infrared spectra and molecular dynamics simulations of trans-HONO isomer in an argon matrix

FTIR temperature dependence studies of the spectra of trans-HONO monomer tr apped in an argon matrix are presented. The spectral studies show that doub lets observed in the N=O, N-O stretching, NOH bending and OH torsion region s and a triplet in the OH stretch region show reversible temperature depend ence; one component of each doublet and two components of the triplet exhib it larger broadening with temperature than the other component in the same region. Molecular dynamics simulations of trans-HONO isomer in an argon mat rix demonstrate the existence of two types of trapping cages. The molecule trapped in a one-atom substitutional cage has more freedom of reorientation al motion than the molecule trapped in a two-atom cage. The bands showing a stronger temperature dependence are assigned to the molecule in a one-atom cage and the others to the molecule in a two-atom cage.