1 Pi - X (1)Sigma(+) band systems of jet-cooled ScCo and YCo

摘要

Rotationally resolved resonant two-photon ionization (R2PI) spectra of ScCo and YCo are reported. The measured spectra reveal that these molecules possess ground electronic states of (1)Sigma(+) symmetry, as previously found in the isoelectronic Cr-2 and CrMo molecules. The ground state rotational constants for ScCo and YCo are B-0(')=0.201 31(22) cm(-1) and B-0(')=0.120 96(10) cm(-1), corresponding to ground state bond lengths of r(0)(')=1.812 1(10) A and r(0)(')=1.983 0(8) A, respectively. A single electronic band system, assigned as a (1)Pi <- X (1)Sigma(+) transition, has been identified in both molecules. In ScCo, the (1)Pi state is characterized by T-0=15 428.8, omega(')(e)=246.7, and omega(')(e)x(e)(')=0.73 cm(-1). In YCo, the (1)Pi state has T-0=13 951.3, omega(')(e)=231.3, and omega(')(e)x(e)(')=2.27 cm(-1). For YCo, hot bands originating from levels up to v(')=3 are observed, allowing the ground state vibrational constants omega(')(e)=369.8, omega(')(e)x(e)(')=1.47, and Delta G(1/2)(')=365.7 cm(-1) to be deduced. The bond energy of ScCo has been measured as 2.45 eV from the onset of predissociation in a congested vibronic spectrum. A comparison of the chemical bonding in these molecules to related molecules is presented. (c) 2007 American Institute of Physics.