title: Small para-hydrogen clusters doped with carbon monoxide: quantum Monte Carlo simulations and observed infrared spectra.
abstract: The structures and rotational dynamics of clusters of a single carbon monoxide molecule solvated in para-hydrogen, (paraH(2))(N)-CO, have been simulated for sizes up to N=17 using the reptation Monte Carlo technique. The calculations indicate the presence of two series of R(0) rotational transitions with J=1<--0 for cold clusters, similar to those predicted and observed in the case of He(N)-CO. Infrared spectra of these clusters have been observed in the region of the C-O stretch ( approximately 2143 cm(-1)) in a pulsed supersonic jet expansion using a tunable diode laser probe. With the help of the calculations, the observed R(0) rotational transitions have been assigned up to N=9 for the b-type series and N=14 for the a-type series. Theory and experiment agree rather well, except that theory tends to overestimate the b-type energies. The (paraH(2))(12)-CO cluster is calculated to be particularly stable and (relatively) rigid, corresponding to completion of the first solvation shell, and it is observed to have the strongest a-type transition.
authors.affiliation: SMC INFM, Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, I-00185 Rome, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Moroni
authors.forename: M
authors.initials: M
authors.lastname: Botti
authors.forename: S
authors.initials: S
authors.lastname: De Palo
authors.forename: A R W
authors.initials: AR
authors.lastname: McKellar