Photodissociation spectroscopy of the Ca+-N-2 complex

摘要

The weakly bound complex Ca+-N-2 is prepared in a pulsed nozzle/laser vaporization cluster source and studied with mass-selected photodissociation spectroscopy. The chromophore giving rise to the electronic transition is the (2)p<--S-2 atomic transition of Ca+. The appearance of spin-orbit doublets in the vibrationally resolved spectrum, as expected for a (2)Pi(r)<--(2)Sigma(+) transition, confirms that the complex is linear. The electronic transition in the complex lies to the red of the atomic resonance line indicating that the complex is more strongly bound in tile excited state than in the ground state. The vibrationally resolved spectrum contains progressions in the Ca+-N-2 stretching mode and in a combination of this stretch with the N-N stretch. Extrapolation of the Ca+-N-2 stretch determines the excited state dissociation energy to be D-0'=6500+/-500 cm(,)(-1) and an energetic cycle determines the ground state value to be D-0''=1755+/-500 cm(-1) (5.02 kcal/mol). The (2)Pi(r)(2,0,0)<--(2)Sigma(+)(0,0,0) vibronic transition has been rotationally resolved yielding the bond lengths: r(CaN)-2.75 Angstrom, and r(NN) = 1.15 Angstrom, for the (2)Sigma(+) ground state; r(CaN) = 2.48 Angstrom and r(NN) =1.17 Angstrom for the (2)Pi excited state. (C) 1998 American Institute of Physics. [References: 57]