High-Resolution Mass-Analyzed Threshold Ionization Study of Deuterated Derivatives of Bis(η<sup>6</sup>-benzene)chromium
作者:Sergey Yu. Ketkov、Heinrich L. Selzle、Edward W. Schlag
DOI:10.1021/om0509950
日期:2006.3.1
Two-color multiphoton mass-analyzed threshold ionization (MATI) spectra of jet-cooled (eta(6)-C6D6)(2)-Cr and (eta(6)-C6D5H)(eta(6)-C6D6)Cr have been obtained for the first time with excitation of the sandwich molecules via vibronic components of the 3d(z2) -> R4p(x,y) Rydberg transition. The ionization energies determined with extremely high accuracy (+/- 0.0004 eV) on the basis of the MATI experiment are 5.4558 and 5.4562 eV, respectively. The simultaneous measurement of the two MATI spectra in one experiment reveals clearly the increase in the ionization energy caused by substitution of one deuterium atorn in (eta(6)-C6D6)(2)Cr with hydrogen. The MATI experiment demonstrates a nonlinear dependence of the ionization potential on the number of deuterium atoms in the bis(eta(6)-benzene)chromium molecule. Deuteration appears to decrease both the ionization energy and the R4p(x,y) Rydberg term value. The decrease in the term value is a result of the Jahn-Teller instability of the R4p(x,y) Rydberg state. The ground-state cation vibrational frequencies of the totally symmetric valence rnetal-ligand stretch v(21) and CH umbrella vibration v(11as) determined from the MATI spectra are, respectively, 249 +/- 3 and 594 +/- 3 cm(-1) for (eta(6)-C6D6)(2)Cr+ and 251 +/- 3 and 595 +/- 3 cm(-1) for (eta(6)-C6D5H) (eta(6)-C6D6)Cr+. These values correspond to the free gas-phase cations.