Three-Photon Excitation of the Lower 0+u Ion-Pair States of Cl2 via a Continuum Intermediate State

Mass-resolved multiphoton ionization spectroscopy of jet-cooled Cl2. I. Bound-free-bound spectroscopy

“…3 and 4 are normalized accordingly. This behavior contrasts markedly with that of the 5s, 6s, and 7s Rydberg states 17 Figure 4 illustrates the large intensity of the ͑2,0͒ band relative to other members of the progression. Irregular intensities such as these are one indication of an interaction with a second electronic state.…”

“…3 cm Ϫ1 . 17 These results are indicative of the lifetime of the 4s Rydberg state being very much shortened by predissociation following interaction with a repulsive state. Thus it is concluded that the ͓ 2 ⌸ 1/2 ͔ c 4s; 1 g state is crossed on its inner or outer wall ͑between vЈϭ1 and vЈϭ2͒, by a 1 ⌸ 1g repulsive valence state with which it interacts weakly.…”

“…35 Cl 2 spectra were recorded by collecting 35 Cl ϩ ions and subsequently subtracting the simultaneously recorded 37 Cl ϩ spectrum. 3 For the vibrational data, a mixture of 150 torr of Cl 2 and 450 torr of He was used while for the rotational data, where less efficient rotational cooling was required, the mixture was 150 torr of Cl 2 and 150 torr of He.…”

“…The method of producing the ␤1 g ( 3 P 2 ) state potential has been described in detail elsewhere. 3 Briefly, the outer limb at RϾ6 Å, corresponding to an energy of ca. 75 000 cm Ϫ1 , is described by a truncated Rittner potential of the form…”

“…[1][2][3][4] Some degree of bond stretching is involved and appreciable intensity is observed when both pump and probe steps have large transition dipole moments. In addition, the wavelength of the probe photon ͑ probe ͒ must lie to shorter wavelengths than the red extremum of the final to intermediate state emission system.…”