1 research outputs found
Spatial Isolation of Conformational Isomers of Hydroquinone and Its Water Cluster Using the Stark Deflector
Conformational isomers
of hydroquinone and their 1:1 clusters with
water have been spatially separated using a Stark deflector in a supersonic
jet. <i>trans</i>-Hydroquinone (HyQ) conformer with zero
dipole moment is little influenced by inhomogeneous electric fields,
whereas <i>cis</i> conformer with nonzero dipole moment
(2.38 D) is significantly deflected from the molecular beam axis into
the direction along which the strong field gradient is applied. Resonant
two photon ionization carried out by shifting the laser position perpendicular
to the molecular beam axis after the Stark deflector then gives an
exclusive S<sub>1</sub>–S<sub>0</sub> excitation spectrum of
the <i>cis</i> conformer only, making possible immaculate
conformer-specific spectroscopy and dynamics. As the spatial separation
is apparently proportional to the effective dipole moment strength,
conformational assignment could be absolute in the Stark deflector,
which contrasts with the hole-burning spectroscopic technique where
identification of a conformational isomer is intrinsically not unambiguous. <i>trans</i>- and <i>cis</i>-HyQ–H<sub>2</sub>O clusters have also been spatially separated according to their
distinct effective dipole moment strengths to give absolute spectroscopic
identification of each cluster isomer, nailing down the otherwise
disputable conformational assignment. This is the first report for
the spatial separation of conformational cluster isomers