A study of the S2(X 3Σ−g) molecule by multiphoton ionization spectroscopy

Multiphoton Ionization/Dissociation of Molecular Sulfur S2 in the UV Region

“…We have observed the dissociation dynamics of superexcited states S 2 ** formed at the three-photon level via the B ( 3 Σ u – ) state at a one-photon level and Rydberg state at a two-photon level; these state lead to formation of electronically excited S* atoms and autoionization. Dyke et al studied the dynamics of superexcited states for molecular sulfur and compared the autoionization and electronically excited S* atoms results for the ground state of molecular sulfur S 2 X 3 Σ g – . From our analysis of TKER distributions, it is clear that the dynamics is dominated by the pathway yielding electronically excited atoms S*(···( 4 S °) 4p 5 P), S*(···( 4 S °) 4p 3 P), S*(···( 4 S °) 4s 3 D °), S*(···( 4 S °) 3d 5 D °), S*(···( 4 S °) 3d 3 D °), S*(···( 4 S °)5s 5 S °), S*(3s 3p 5 3 P °) from dissociation of the S 2 ** state, which are subsequently ionized with a fourth photon.…”

“…Exposure of S 2 to high-intensity light from a focused, pulsed, tunable dye laser, such as that needed for (2 + 1) REMPI detection of S atoms, can lead to multiphoton ionization of S 2 , as first reported by Dyke and co-workers and in detailed studies by Cooper and Western, who showed that three-photon ionization can be resonance enhanced at the one-photon level via the X 3 Σ g – – B 3 Σ u – and X 3 Σ g – – B ″ 3 Π u + bands and at the two-photon level by the (3dπ) 3 Δ g Rydberg state and the 2 5 Σ g – ion-pair state. It may thus be expected that stepwise multiple photon photodissociation of S 2 is a means of producing S atoms.…”

“…While molecular sulfur has been studied extensively by experiments − and theory − over the last decades, its photoexcitation dynamics are still unclear due to its complexity and to spin–orbit coupling between its manifold of states. Our laboratory studies of S 2 use a discharge system in which diatomic sulfur is produced in the discharge and then allowed to interact with intense laser light.…”

Resonance enhanced multiphoton ionization spectroscopy of the NF molecule: 1,3Φ 3d and 4d Rydberg states

“…[1][2][3] As in our earlier work, 1 NF was produced on the inlet line of the spectrometer by making use of the rapid gas-phase reactions:…”

“…As can be seen, better agreement is obtained with the experimental spectrum for the first set of constants in Table II, with a ϭ159 cm Ϫ1 , in terms of reproduction of the observed band contours and the relative intensity of the singlet and triplet components. As a further attempt to decide between the two sets of 1,3 ⌽ constants, experiments were performed to observe the 3 ⌽ state in a 3ϩ1 MPI process from the X 3 ⌺ Ϫ state of NF. A three-photon resonant 3 ⌽← 3 ⌺ Ϫ transition should show the reverse picture to that described earlier, with the allowed 3 ⌽← 3 ⌺ Ϫ band being more intense than the 1 ⌽← 3 ⌺ Ϫ band.…”