Cluster ion dip spectroscopy of hydrogen bonded phenol(H sub 2 O) sub n clusters, n =0--4
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 (USA)
Employing a laser based time-of-flight mass spectrometer system, ion dip spectra for phenol (Ph), Ph(H{sub 2}O){sub 1}, Ph(H{sub 2}O){sub 3}, and Ph(H{sub 2}O){sub 4} were obtained in the range of 500--1300 cm{sup {minus}1} from a variety of initially pumped states. Dramatic enhancement of the signal-to-noise ratio of the cluster ion dip spectra relative to that of the bare phenol is attributable to the increase in the excited state singlet lifetime of the hydrated phenol chromophore. Several dips in the Ph(H{sub 2}O){sub 1} spectrum exceed the saturation'' limit of 50%, indicating that significant relaxation of the downpumped ground state is occurring via low frequency vibrational modes of the H{sub 2}O solvent bath.'' Excitation of the hydrogen bond stretch ({sigma} {sup 1}{sub 0}=156 cm{sup {minus}1} ) in the {ital S}{sub 1} state of the Ph(H{sub 2}O){sub 1} cluster reveals that the ground state ({ital S}{sub 0}) hydrogen bond stretch, {sigma} {sup 0}{sub 1}, is 151({plus minus}1) cm{sup {minus}1}, a mode which appears to be built off of phenol fundamental and combination bands. A second intermolecular band is also evident at 141({plus minus}2) cm{sup {minus}1}. There is no evidence of an analogous wag mode when pumping the {ital S}{sub 1} bend ({beta}{sup 1}{sub 0}), suggesting that the intermolecular modes in {ital S}{sub 1} are highly coupled. Attempts to obtain ion dip spectra for Ph(H{sub 2}O){sub 2} went unrewarded, presumably due to the anomalously short {ital S}{sub 1} lifetime of the Ph(H{sub 2}O){sub 2} cluster. Spectra for Ph(H{sub 2}O){sub 3} and Ph(H{sub 2}O){sub 4} were obtained which show prominent phenol bands, with low frequency ({similar to}10 cm{sup {minus}1} ) progressions built off of these bands.
- DOE Contract Number:
- FG02-88ER60648
- OSTI ID:
- 5486211
- Journal Information:
- Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 94:12; ISSN JCPSA; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
AGGLOMERATION
AROMATICS
CHEMICAL BONDS
ENERGY LEVELS
EXCITED STATES
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
ION SPECTROSCOPY
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHENOL
PHENOLS
SPECTROSCOPY
VIBRATIONAL STATES
WATER