title: Near-infrared spectroscopy of ethylene and ethylene dimer in superfluid helium droplets.
abstract: The nu(5)+nu(9) spectra of ethylene, C(2)H(4), and its dimer, solvated in helium nanodroplets, have been recorded in the wavelength region near 1.6 microm. The monomer transitions show homogeneous broadening of approximately 0.5 cm(-1), which is interpreted as due to an upper state vibrational relaxation lifetime of approximately 10 ps. Nearly resonant vibrational energy transfer (nu(5)+nu(9)-->2nu(5)) is proposed as the relaxation pathway. The dimer gives a single unresolved absorption feature located 4 cm(-1) to the red of the monomer band origin. The scaling of moments of inertia upon solvation in helium is 1.18 for the monomer and >2.5 for the dimer. In terms of the adiabatic following approximation, this classifies the monomer as a fast rotor and the dimer as a slow rotor.
authors.affiliation: Department of Chemistry, Princeton University, Princeton, NJ 08544, USA. ischeele@alumni.princeton.edu
authors.forename: Iris
authors.initials: I
authors.lastname: Scheele
authors.forename: André
authors.initials: A
authors.lastname: Conjusteau
authors.forename: Carlo
authors.initials: C
authors.lastname: Callegari
authors.forename: Roman
authors.initials: R
authors.lastname: Schmied
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Lehmann
authors.forename: Giacinto
authors.initials: G
authors.lastname: Scoles