The origin of the ArI 2 BX continuum

“The origin of the Ar···I 2 B–X continuum excitation signal below and above the I 2(B) dissociation limit: Bound-free transitions of the linear complex. ” Richard A. Loomis Washington University in St. Louis Department of Chemistry June 21, 2005 OSU 60 th International Symposium on Molecular Spectroscopy

Electronic Spectroscopy of Rg···dihalogen Complexes T-shaped • He···I 2 • Ne···I 2 (Levy, ’ 80) (Heaven, ’ 02) • • • (Janda, ’ 88) (Janda, ’ 84 & ’ 89) (Janda, ’ 88) (Janda, ’ 91) • He···ICl (Lester, ’ 85) (Janda, ’ 90) • Ne···ICl (Lester, ’ 85) He···Cl 2 Ne···Cl 2 Ar···Cl 2 Kr···Cl 2 Xe···Cl 2 • He···Br 2 (Janda, ’ 96, ’ 02) • Ne···Br 2 (Janda, ’ 88, ’ 03; Stephenson, ’ 97) Both Linear & T-shaped • Ar···I 2 (Klemperer, ’ 93; Heaven, ’ 01) • Ne···I 2 (Heaven, ’ 02)

I 2 Electronic Potentials

LIF Spectrum of I 2 in Ar/He

Spectroscopy of Ar···I 2 Complexes (I 2 B–X, 22– 0 Region) T-shaped Ar···I 2 He···I 2 50 2% Ar in He (20 psi) T-shaped Ar 2···I 2 Linear Ar···I 2

Ar + I 2 Intermolecular Interactions: • Discrepancies and disagreements between the details of the Ar + I 2(X, v²=0) and Ar + I 2(B, v¢) PESs

Spectroscopy of Ar···I 2 Complexes (I 2 B–X, 22– 0 Region) T-shaped Ar···I 2 He···I 2 50 2% Ar in He (20 psi) T-shaped Ar···I 2 T-shaped Ar 2···I 2 Linear Ar···I 2

Determining the Linear He···I 35 Cl(X) Binding Energy hn. ICl He + ICl(B, v¢=2) Energy (cm– 1) 17640 hn. ICl 17620 He + ICl(X, v²=0) hn. He···ICl 0 L D 0 ² – 20 – 40 Linear He···ICl T-shaped He···ICl – 60 4 5 He–ICl Distance (Å) 6 = 22. 0(2) cm– 1

Determining the Linear Ar···I 2(X) Binding Energy hn. I 2 Ar + I 2(B, v¢=20) 18200 Energy (cm– 1) 18100 hn. I 2 18000 17900 hn. Ar···I 2 0 L D 0 ² Ar + I 2(X, v²=0) – 100 – 200 Linear Ar···I 2 T-shaped Ar···I 2 – 300 3 4 5 6 Ar–I 2 Distance (Å) 7

Linear Ar···I 2 Bound–Free Transitions (I 2 B–X, 20– 0 Region)

Determining the Linear Ar···I 2(X) Binding Energy hn. I 2 Ar + I 2(B, v¢=20) 18200 Energy (cm– 1) 18100 hn. I 2 18000 17900 hn. Ar···I 2 0 L D 0 ² Ar + I 2(X, v²=0) – 100 L D 0 ² = 250(2) cm– 1 DT 0 ² = 236(3) cm– 1 – 200 Linear Ar···I 2 T-shaped Ar···I 2 – 300 3 4 5 6 Ar–I 2 Distance (Å) 7

Spectroscopy of Ar···I 2 Complexes (I 2 B–X, 22– 0 Region) T-shaped Ar···I 2 He···I 2 50 2% Ar in He (20 psi) T-shaped Ar···I 2 T-shaped Ar 2···I 2 Linear Ar···I 2

Ar + I 2 Vibrational Predissociation: I 2 E–B

Identifying Ar···I 2 Transitions (I 2 B–X, 20– 0 Region) Probe: I 2 b–B, 0– 20

Spectroscopy of Ar···I 2 Complexes – Theory (I 2 B–X Region)

Spectroscopy of Ar···I 2 Complexes (I 2 B–X, 22– 0 Region) T-shaped Ar···I 2 He···I 2 50 2% Ar in He (20 psi) T-shaped Ar···I 2 T-shaped Ar 2···I 2 Linear Ar···I 2

LIF Spectrum of I 2 in Ar/He

Action Spectra of I 2 in Ar I 2(B)

Continuum Signals in Ar···I 2 Spectrum – Bound-free Transitions of the Linear Conformer I 2 P 1/2 + I 2 P 3/2 Ar + I 2(B, v¢=36) hn Ar + I 2(B, v¢=28) Ar + I 2(X, v²=0)