(2 + 1) REMPI spectra of the I₂–Krand I₂–N₂van der Waals complexes and the (2 + 1′) ZEKE–PFI photoelectron spectrum of I₂⁺–Kr

Abstract

We present the (2 + 1) mass-resolved resonance-enhanced multiphoton ionisation (REMPI) spectrum of the [²Π_3/2]_c5d;Ω_g (Ω = 0,2) Rydberg states of the I₂–Kr van der Waals complex. Anharmonic progressions in the I₂···Kr van der Waals stretching mode have been observed with [small omega, Greek, tilde]_e values of 49 ± 2 and 47 ± 2 cm⁻¹ for the [²Π_3/2]_c5d;Ω = 0_g and [²Π_3/2]_c5d;Ω = 2_g states, respectively. The [²Π_3/2]_c5d;Ω = 2_g state of I₂–Kr has been used as an intermediate in a two-colour (2 + 1′) zero kinetic energy pulsed-field ionisation (ZEKE–PFI) photoelectron study of the X̃²Π_3/2,g state of the I₂⁺–Kr ionic complex. The adiabatic ionisation energy was determined to be 74248 ± 3 cm⁻¹. An anharmonic vibrational progression in the I₂⁺···Kr van der Waals stretching mode was observed giving a value of [small omega, Greek, tilde]_e = 55 ± 2 cm⁻¹ for the X̃²Π_3/2,g state of the complex. The [²Π_1/2]_c6s;Ω = 1_g Rydberg state of the I₂–N₂ van der Waals complex has also been observed using REMPI spectroscopy. Anharmonic progressions in the I₂···N₂ van der Waals stretching mode have been observed with [small omega, Greek, tilde]_e = 71 ± 2 cm⁻¹. Comparisons are made between the spectroscopic data obtained for the Rydberg states of I₂–Kr and I₂–N₂ with the analogous Rydberg states in I₂–Ar.