Mohammed Gharaibeh, Fumie X. Sunahori, and Dennis J. Clouthier Department of Chemistry, University of Kentucky Riccardo Tarroni Dipartimento di Chimica Industriale “Toso Montanari”, Universitá di Bologna

2 Industrial Significance  Boron-containing free radicals Chemical vapor deposition Semiconductor doping Etching of circuit elements  BH 2 In situ detection of BH 2 by the Atkinson group 1  Intracavity laser spectroscopy  Plasma dissociation of B 2 H 6 Similar condition used in the industrial boron deposition and boron-containing films 1: D. C. Miller, J. J. O’Brien, and G. H. Atkinson, J. Appl. Phys. 65, 2645 (1989).

3 Background  Experimental Studies Absorption spectrum in the nm region 2 Flash photolysis of H 3 BCO Linear-bent transition: 2 B 1 ( П u ) – 2 A 1 Ground state geometry determined Electron spin resonance spectrum in Ar matrix by Knight, Jr. et al. (1989): 3 Hyperfine parameter determined 2: G. Herzberg and J. W. C. Johns, Proc. R. Soc. London, 298A, 142 (1967). 3: L. B. Knight, Jr., M. Winiski, P. Miller, C. A. Arrington, and D. Feller. J. Chem. Phys. 91, 4468 (1989).

Linear-Bent Transition 4 X 2 A 1 : (2a 1 ) 2 (1b 2 ) 2 (3a 1 ) 1 A 2 B 1 : (2a 1 ) 2 (1b 2 ) 2 (1b 1 ) 1 Θ = ° r e = Å Θ = 180 ° r e = Å 2Пu2Пu ~ ~ CCSD(T)/cc-pV5Z calculations

5 Background  Theoretical Studies Perić et al. (1980) 4  Renner-Teller coupling and large amplitude motion Re-numbered v 2 ′ Brommer et al.(1992) 5  3-D PES’s Anharmonicity, rotation-vibration, and electronic angular momenta coupling Rovibronic energies calculated by variational method Kolbuszewski et al.(1996) 6  Spin-orbit coupling included 4: M. Perić, S. D. Peyerimhoff, and R. J. Buenker, Can. J. Chem, 59, 1318 (1981). 5: M. Brommer, P. Rosmus, S. Carter, and N. C. Handy. Mol. Phys. 77, 549 (1992). 6: M. Kolbuszewski, P. R. Bunker, W. P. Kraemer, G. Osmann, and P. Jensen. Mol. Phys. 88, 105 (1996).

Pulsed Discharge Jet Apparatus 6 Gas Mixture: 0.5% B 2 H 6 or B 2 D 6 in 40 psi Ar Products: 11 BH 2, 10 BH 2, 11 BD 2, and 10 BD 2

7 LIF Spectra (0,2 15,0) Mohammed 10 BH 2 10 BD 2

8 Linear-Bent Transition v 2 =0 2 П 1/2 1 2 П 3/2 2A12A1 2B1(П)2B1(П) v 2 =1 v 2 =2 K П 1/2 2 П 3/2 2 П 1/2 2 П 3/2 2 Ф 5/2 2 Ф 7/2 2 Σ 1/2 2 Δ 5/2 2 Δ 3/2 K = | ± Λ ± l | = |1 ± l | 2П2П v 2 =1 v 2 =2 K 1 0 KaKa v 2 =0 v 2 = B1(П)1B1(П) 1A11A1 1П1П  K a = ±1 Σ П

LIF Spectra 9 v 2 ′ = v 2 ′= П Σ Σ Σ Σ Σ П П П П П П П П П П Σ Σ Σ Σ Σ

10 BH 2 (0,2 10,0) П Band 2B1(П)2B1(П) П 01 1 K a " = K a " =  K a = ±1  K c = 0, ±2 2A12A1

11 BH 2 (0,2 15,0) Σ and Δ Bands 11 BH 2 10 BH 2 p R 1 (1) B1(П)2B1(П) Σ Δ A12A1 K a " = 1 r R 1 (1)

12 Theoretical Study Riccardo

V5Z: CCSD(T)/cc-pV5Z, only valence electron correlated Calc. – Expt. (cm -1 ) 11 BH 2 Band Origin (cm -1 ) V5Z+CC: CCSD(T)/cc-pV5Z + core electron correlation CBS+CC+DFCI+DBOC: complete basis set extrapolation + core electron correlation+ residual valence correlation beyond triple excitations +diagonal Born- Oppenheimer correction (isotope effect) CBS+CC: complete basis set extrapolation + core electron correlation CBS+CC+DFCI: complete basis set extrapolation + core electron correlation+ residual valence correlation beyond triple excitations Theory vs Experiment 13

LIF Spectra 14 v 2 ′ = v 2 ′= (1,v 2,0)

15 Ground State Molecular Structure K a " = K a " = BH 2 2B1(П)2B1(П) 2A12A1 4(A-B) – 11 BD K a " = K a " = F(J,K a ) = (A-B)K a 2 + BJ(J+1) – – A= 41.6 cm -1 A= 23.3 cm -1

16 High-Resolution LIF Spectrum ( 11 BD 2 ) K′=1←K a " =0 K′=1←K a " =2 (0,2 20,0) П Mohammed pR(N")pR(N") rR(N")rR(N") pQ(N")pQ(N") pP(N")pP(N") rQ(N")rQ(N") rP(N")rP(N")

17 Molecular Structure 129.6(2)º [129.9º] [Theory: CCSD(T)/cc-pV5Z] (2) Å [1.195 Å] Rotational Constants 11 BH 2 *11 BD 2 A0A (8)23.321(1) B0B (1)3.627(2) C0C (2)3.094(2) *Herzberg and Johns Å, 131º

18 11 BH 2 Emission Spectrum K a ' = 1 Relative Energy (cm -1 ) v" = 0 v 2 " = 1 v 2 " = 2 v 1 " = 1 Pump r R 0 (1) (0,2 12,0) П K a " = 2 K a " = 0 Pump  K a = ±1  K c = 0, ±2

19 Ground State Energy Levels cm -1 (v 1, v 2, v 3 )N Ka Kc Expt. (±2)Calc.Calc. – Expt. (0,1,0) (0,2,0) (1,0,0)

20 Summary LIF spectra of 11 BH 2, 10 BH 2, 11 BD 2, and 10 BD nm Calculations of ro-vibronic energy levels Including the spin-orbit effect Pure ab initio High-Resolution LIF spectrum of 11 BD 2 Ground state molecular structure refined Emission spectra of 11 BH 2 and 11 BD 2  Ground state vibrational energy levels

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