High resolution infrared spectra of HeN–CO2 clusters with N up to about 20 have been studied in the region of the CO2 v3 fundamental band. The B rotational constant initially drops as expected for a normal molecule, reaching a minimum for N = 5. Its subsequent rise for N = 6 to 11 can be interpreted as the transition from a normal (though floppy) molecule to a quantum solvation regime. For N > 13, the B value becomes approximately constant with a value about 17% larger than that measured in much larger helium nanodroplets. Quantum Monte Carlo calculations of pure rotational spectra are in excellent agreement with the measured B in this size range, and complement the experimental study with detailed structural information. For larger cluster size (N = 30-50) the simulations show a clear sign of convergence towards the nanodroplet B value.
en-copyright= kn-copyright= en-aut-name=TangJian en-aut-sei=Tang en-aut-mei=Jian kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=McKellarRobert A en-aut-sei=McKellar en-aut-mei=Robert A kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=MezzacapoFabio en-aut-sei=Mezzacapo en-aut-mei=Fabio kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=MoroniSaverio en-aut-sei=Moroni en-aut-mei=Saverio kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Okayama University affil-num=2 en-affil= kn-affil=Steacie Institute for Molecular Science affil-num=3 en-affil= kn-affil=Università di Roma La Sapienza affil-num=4 en-affil= kn-affil=Università di Roma La Sapienza en-keyword=infrared spectroscopy kn-keyword=infrared spectroscopy en-keyword=helium cluster kn-keyword=helium cluster en-keyword=molecular superfluidity kn-keyword=molecular superfluidity en-keyword=computer simulation kn-keyword=computer simulation END start-ver=1.4 cd-journal=joma no-vol=123 cd-vols= no-issue=11 article-no= start-page= end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2005 dt-pub=20059 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Infrared spectra of seeded hydrogen clusters: (para-H2)N-N2O and (ortho-H2)N-N2O, N=2-13 en-subtitle= kn-subtitle= en-abstract= kn-abstract=High-resolution infrared spectra of clusters containing para-H2 and/or ortho-H2 and a single nitrous oxide molecule are studied in the 2225-cm–1 region of the 1 fundamental band of N2O. The clusters are formed in pulsed supersonic jet expansions from a cooled nozzle and probed using a tunable infrared diode laser spectrometer. The simple symmetric rotor-type spectra generally show no resolved K structure, with prominent Q-branch features for ortho-H2 but not para-H2 clusters. The observed vibrational shifts and rotational constants are reported. There is no obvious indication of superfluid effects for para-H2 clusters up to N=13. Sharp transitions due to even larger clusters are observed, but no definite assignments are possible. Mixed (para-H2)N–(ortho-H2)M–N2O cluster line positions can be well predicted by linear interpolation between the corresponding transitions of the pure clusters.
en-copyright= kn-copyright= en-aut-name=TangJian en-aut-sei=Tang en-aut-mei=Jian kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=McKellarRobert A en-aut-sei=McKellar en-aut-mei=Robert A kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= affil-num=1 en-affil= kn-affil=Okayama University affil-num=2 en-affil= kn-affil=Steacie Institute for Molecular Science en-keyword=vibrational kn-keyword=vibrational en-keyword=rotational kn-keyword=rotational en-keyword=infrared spectroscopy kn-keyword=infrared spectroscopy en-keyword=gas phase kn-keyword=gas phase en-keyword=superfluidity kn-keyword=superfluidity END