Electronic transitions of ScP N. Wang, Y. W. Ng, K. F. Ng, and A. S.-C. Cheung Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong Paper - TK 04 International Symposium on Molecular Spectroscopy 69th Meeting - June 16-20, Champaign-Urbana, Illinois

Acknowledgements Graduate Students:Miss Na Wang Mr. Tony Y. W. Ng Mr. Ken Ng Funding Agents: Research Grants Council, HKSAR Committee on Research & Conference Grants, HKU

Introduction Sc diatomic molecules are interesting: Spectroscopic interest:  Sc : 4s 2 3d 1 atomic configuration  With only one electron in the d orbital, it is an ideal system for studying chemical bonding of the d orbital

Background  F. Tiengeta & J. F. Harrison (1994) Chem. Phys. Lett., 223, 202. ~ performed MCSCF level calculations and predicted a X 1  + state and several low-lying 1 , 3  + and 3  electronic states.  A. Daoudi, M. F. Baba S. Elkhattabi, F. Rogemond & H. Chermette (2003) Mol. Phys. 101, 292. ~ performed CASSCF, CIPSI, and DFT calculations and predicted the bonding of the X 1  + involve an open-shell state.  G.M.S. Tong, G.H. Jeung and A.S-C. Cheung (2003) J. Chem. Phys. 118, 9224 ~ performed DFT calculations and predicted the spectroscopic properties of the X 1  + and a few low-lying excited states.  Z. Liao, Y. Xia, M-C. Chan & A. S-C. Cheung (2012) Chem. Phys. Lett. 551, 60. ~ analyzed the LIF spectrum in the near IR region between and nm. ~ the [11.9] 1  + - X 1  + transition and determined the X 1  + ground state.

Experimental technique: laser vaporization/reaction free jet expansion and laser induced fluorescence spectroscopy 2%PH 3 /Ar Sc rod

Experimental Conditions Laser ablation reaction: Sc (atom) + 2% PH 3 / Ar → ScP + etc. Ablation Laser: Nd:YAG, 10Hz, 532nm, ~5 mJ Gas Pressure: 6 atm (argon + reagent gas) Background pressure: 5x10 -5 Torr. Excitation Lasers:  Optical parametric oscillator (OPO) system pumped by Nd:YAG 355nm.  A dye laser pumped by Nd:YAG laser

Results and analysis: Two new electronic transition systems: the [19.0] 1  + - X 1  + and [19.8] 3  + - a 3  + transitions [19.0] 1  + [19.8] 3  + a3+a3+ Our apology: the [19.8] 3  - a 3  transition listed in the ABSTRACT is not correct. Earlier work

The (3, 0) band of [19.0] 1  + - X 1  + Electronic Transition P branch R branch Only P and R branches

Results from least squares fittings: The analysis included v= 0, 1, 3 and 4 The (2, 0) band overlaps with a triplet transition band The observed rotational lines were fitted to the expression: = o + B' J' (J' + 1) - D' [J' (J' + 1)] 2 - {B" J" (J"+ 1) – D" [J"(J" + 1)] 2 } State v v 0 B [19.0] 1  (9) (5) (7) (8) (7) (2) (9) (2)

The (1, 0) band of [19.8] 3  + - a 3  + Transition R branches P branches

(1, 0) band of [19.8] 3  + - a 3  + transition : This triplet transition: 1. Initially, lines were fitted to the expression: = o + B eff ’ J’ (J’ + 1) - D eff ’ [J’ (J’ + 1)] 2 - {B eff ” J” (J” + 1) – D eff ” [J”(J” + 1)] 2 } 2. Effective Hamiltonian (Subsequently) RMS error = 0.05 cm -1 [19.8] 3  + v = 1 T 1 = (9) B = (3)  = (7) a3+a3+ v = 0 B = (3) = 0.52(7)

The (0,0) band of [19.8] 3  + - a 3  + transition is perturbed R branches P branches

The (0,0) band of [19.8] 3  + - a 3  + transition is perturbed We could not fit all the lines to the 1. Effective Hamiltonian 2. The F 2 component is perturbed [19.8] 3  + v = 0 3  ±1 : T 0 = (2) ; B = (2) 3  0 : T 0 = (3) ; B = (2) a3+a3+ v = 0 B = (3) = 0.52(7)

The (0,0) band of [19.8] 3  + - a 3  + transition is perturbed Two perturbations were found for the F2 component of the upper state. at J = 10 and 22 Reduced term value plot vs N(N+1) showing the perturbations

Resolved fluorescence spectrum of (0,0) band of [19.8] 3  + - a 3  + transition The  G 1/2 the a 3  + state was estimated to be 495  15 cm -1

Molecular constants determined for ScP (cm -1 ) State T0T0 B0B0  G 1/2 R e (Ǻ) [19.8] 3  + a [19.0] 1  [11.9] 1  a3+a3+ a * X1+X1 * Value estimated from resolved fluorescence spectrum a is the origin of the a 3  + state

State ParameterExperimental Theoretical TH[1] DBERC[2]TJC[3] MCSCF CIPSI B-P86 DFT A 1 Σ + or [11.9] 1  + T e B e ω e r e a 3 Σ + T e B e ω e r e a * 495* * X 1 Σ + B e ω e r e [1] F. Tiengeta & J. F. Harrison (1994) Chem. Phys. Lett., 223, 202. [2] A. Daoudi, M. F. Baba S. Elkhattabi, F. Rogemond & H. Chermette (2003) Mol. Phys. 101, 292 [3] G.M.S. Tong, G.H. Jeung and A.S-C. Cheung (2003) J. Chem. Phys. 118, 9224 Comparison of molecular constants for ScP cm -1 * B 0,  G 1/2 and r 0

Molecular Orbital and Electronic Configurations of ScP Configurations: X 1  + : 1  2 1  4 2  2 & 1  2 1  4 2  1 3  1 a 3  + : 1  2 1  4 2  1 3  1 A 1  + : 1  2 1  4 2  2 ScCl ScS 3 e 5 e

Comparison of diatomic molecules of Sc and nearby main group elements ScP 1Σ+1Σ+ 12142131& 12142212142131& 12142 ScN 1Σ+1Σ+ 12142131& 12142212142131& 12142 ScO 2Σ+2Σ+ 121422311214223 ScS 2Σ+2Σ+ 121422311214223 ScCl 351Σ+1Σ+ 121422321214223 MoleculeGround state Electronic Config. B e /cm -1 ω e /cm -1 R e (Ǻ)

Summary 20 (1)A new triplet [19.8] 3  + - a 3  + transition has been recorded and analysis. (2)The bond length of the ground X 1  + state of ScP is relatively long, which agrees well with theoretical value from admixture of 1  2 1  4 2  1 3  1 & 1  2 1  4 2  2. (3)The a 3  + state has similar bond length, which should also be arisen from the 2  1 3  1 configuration as in the ground state.

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