Internal Rotation and Spin Conversion of CH3OH in Solid para-Hydrogen
Yuan-Pern Lee,1,2*
Yu-Jong Wu,3
R. M. Lees,4
Li-Hong Xu,4
Jon T. Hougen5
The quantum solid para-hydrogen (
p-H
2) has recently proven useful
in matrix isolation spectroscopy. Spectral lines of compounds
embedded in this host are unusually narrow, and several species
have been reported to rotate in
p-H
2. We found that a
p-H
2 matrix
inhibits rotation of isolated methanol (CH
3OH) but still allows
internal rotation about the C–O bond, with splittings
of the E/A torsional doublet in internal rotation–coupled
vibrational modes that are qualitatively consistent with those
for CH
3OH in the gaseous phase. This simplified high-resolution
spectrum further revealed the slow conversion of nuclear spin
symmetry from species E to species A in the host matrix, offering
potential insight into nuclear spin conversion in astrophysical
sources.
2 Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
3 Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang Fu Road, Hsinchu 30013, Taiwan.
4 Centre for Laser, Atomic and Molecular Sciences, Department of Physical Sciences, University of New Brunswick, 100 Tucker Park Road, Saint John, New Brunswick E2L 4L5, Canada.
5 Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
* To whom correspondence should be addressed. E-mail: yplee{at}mail.nctu.edu.tw
