1. Detection of the H 2 PS free radical by laser spectroscopy Robert Grimminger *, Dennis J. Clouthier *, and Riccardo Tarroni † * Department of Chemistry, University of Kentucky, Lexington KY † Dipartimento di Chimica Fisica ed Inorganica, Università di Bologna, 40136 Bologna, Italy

2. Why study H 2 PS? Phosphorus? Spin labels

3. Production of jet-cooled radicals 5% H 2 in Ar H 2 PS Cl 3 PS (liq.) 3% H 2 in Ar + 3% D 2 in Ar 5% D 2 in Ar D 2 PS H 2 PS D 2 PS HDPS

4. Molecular orbitals of H 2 PS π (12a ′) n (4a ″) π* (13a ′) Energy (cm -1 ) 04,60020,800 Calculations done by Riccardo Tarroni using CCSD and CCSD-EOM using aug-cc-pV(T+d)Z basis

5. Calculated geometry for lowest electronic states State r (P  S) År (P  H)Å  (HPS)°  (HPH)°  (oop)° X̃ 2 A 1.9791.402109.099.859.7 Ã 2 A  2.1391.41394.290.484.1 B̃ 2 A 2.1141.411109.994.459.9 a c b H H P S θ CCSD and CCSD-EOM using aug-cc-pV(T+d)Z basis

6. Low resolution LIF spectra ν 2 = PH sym. Bend ν 3 = PS stretch ν 4 = HPH wag Calc. = CCSD and CCSD-EOM using aug-cc-pV(T+d)Z basis Obs. isotope shift = 2.9 cm -1 Calc. isotope shift = 3.0 cm -1 Constant H 2 PSD 2 PS obs.calc.obs.calc. ω 1 0 (a´)···2394···1719 ω 2 0 (a´)1062.1(6)1137770.0(3)817 ω 3 0 (a´)470.3(5)525451.4(2)492 ω 4 0 (a´)823.9(10)843643.0(5)661 ω 5 0 (a˝)···2402···1730 ω 6 0 (a˝)···670···486 x 33 ···-6.3(1) x 34 -7.8(4)-4.5(1) x 44 -2.9(1)-2.55(3)

7. Total LIF of a mixture of isotopologs H 2 PS D 2 PS HDPS

8. Pump Laser Tunable Dye laser Synchronous-scan LIF technique PMT 15000160001700018000190002000021000220002300024000 Laser: Offset: 450 cm -1

9. HDPS sync-scan LIF

10. Analysis of emission spectra Calc. =CCSD and CCSD-EOM using aug-cc-pV(T+d)Z basis ν 2 = PH sym. Bend ν 3 = PS stretch ν 4 = HPH wag Constant (cm -1 ) H 2 PSD 2 PSHDPS obs.calc.obs.calc.obs.calc. ω 1 0 (a´)···2446···1751···2455 ω 2 0 (a´)1088.7(14)1142812.2(9)824976.7(4)1007 ω 3 0 (a´)681.1(4)694613.3(3)614594.8(2)600 ω 4 0 (a´)481.1(4)422389.0(4)349429.1(4)382 ω 5 0 (a˝)···2465···1776···1763 ω 6 0 (a˝)···782···568698(1)721

11. High-resolution of the H 2 PS 0 0 band 0

12. Geometry of H 2 PS Calculated out-of-plane angle MoleculeX̃X̃B̃ H 2 PO48°67° H 2 AsO59°70° H 2 PS60° Cl 2 PS47°63° F 2 PS49°67° H H P S θ Out-of-plane angle CCSD and CCSD-EOM using aug-cc-pV(T+d)Z basis Constant (cm -1 ) X̃X̃B̃B̃ A[4.85402]4.727(5) [4.93042] B0.2517(4) [0.249317] 0.2137(5) [0.219462] B-C [0.4502×10 -2 ] [0.2570×10 -2 ] ε aa [-0.42758]0.155(4) T0T0 20004.337(4) –

13. Walsh diagram for H 2 PS system Orbital energies at B3LYP/aug-cc-pV(T+d)Z for H 2 PS anion

14. Conclusions First spectroscopic observation of H 2 PS H 2 PS has been characterized by LIF and SVL emission spectroscopy Our analysis identifies the observed transition as B̃ 2 A´–X̃ 2 A´, as predicted by our ab initio calculations