1. Ramya Nagarajan, Jie Yang and Dennis J. Clouthier A spectroscopic study of the linear-bent electronic transitions of jet-cooled HBCl and BCl 2 And The electronic spectra of jet-cooled BC

2.  BCl 2 & HBCl * Reactive intermediates: CVD (BCl 3 (NH 3 /H 2 )) and plasma etching (BCl 3 /Ar ) processess * Spectroscopically interesting: Linear-Bent systems & Renner- Teller effect  BC * Boron carbide (B 4 C): extremely hard, chemically inert, high neutron absorbing cross section * Used in bulletproof vests, nuclear reactor control rods, abrasive for cutting * High resolution gas phase study of B-X and C-X transitions in BC Why study?

3. BCl 3 /H 2 /Ar B(CH 3 ) 3 /Ar Pulsed valve Ring electrodes BCl 2, HBCl BC Pulsed Discharge Source

4. Pumping Laser Tunable Dye laser Oscilloscope + Gated integrators Computer PMT Monochromator Experimental Setup

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

6.  BCl 2 * Matrix isolation studies: IR spectra showing activity in sym stretch ν 1 and asym stretch ν 3 Hassanzadeh and Andrews, J. Phys. Chem. 97, 4910 (1993) * VUV photoexcitation spectroscopy of BCl 3 : Emissions from BCl 2 in 400-650nm and 200-500nm region Jochims et al, J. Phys. B: At. Mol. Opt. Phys. 32. 2569 (1999)  HBCl * Gas phase emission spectra recorded Clouthier et al, J. Am. Chem. Soc. 127, 10814 (2005) Background

7. BCl 2 : 17 valence electrons GS: (a 2 ) 2 (b 2 ) 2 (a 1 ) 1 (b 2 ) 0 : 2 A 1 ES: (a 2 ) 2 (b 2 ) 2 (a 1 ) 0 (b 2 ) 1 : 2 B 1 HBCl: 11 valence electrons GS: (a ” ) 2 (a’) 2 (a’) 1 (a ” ) 0 : 2 A ’ ES: (a ” ) 2 (a’) 2 (a’) 0 (a ” ) 1 : 2 A ” Walsh diagram σ σ σ σ πa" π a' a" σuσu σuσu σgσg σgσg σuσu σgσg πuπu πgπg πuπu a1a1 b1b1 b2b2 b1b1 b2b2 b2b2 b2b2 a1a1 a1a1 a1a1 a2a2 a1a1 <XBX<HBX

8. v2v2 K=l+  3 2 1 0 1 0 2 0 1 3 1 0 2 4 2 0             2Π2Π 2A12A1 180160140120100 < XBX/HBX Renner-Teller effect in Linear-Bent systems

9. HBCl LIF spectrum A 2 A"П←X 2 A′ system ~ ~

10. K a " = 0 K a " = 2 K a ' = 1 F(J,K a ) = (A-B)K a 2 + BJ(J+1)  K a = ±1 H 11 B 35 Cl H 10 B 35 Cl ν 2 : HBCl bend ν 3 : BCl stretch Π Σ Emission spectra: HBCl 0 2121 3131

11. H 11 B 35 Cl H 10 B 35 Cl ΣΠΣΣΣΠΠΠ Sync-scan LIF: HBCl

12. BCl 2 LIF spectrum A 2 B 1 П ← X 2 A 1 system ~~

13. BCl 2 LIF spectrum A 2 B 1 П ← X 2 A 1 system ~~

14. 11 BCl 2 10 BCl 2 Sync-scan LIF: BCl 2 Total LIF

15. 11 B 35 Cl 35 Cl 11 B 35 Cl 37 Cl 11 B 37 Cl 37 Cl 10 B 35 Cl 35 Cl 10 B 35 Cl 37 Cl 10 B 37 Cl 37 Cl ω10ω10 700.17(24)695.87(24)692.31(37)723.28(41)719.56(42)716.57(29) ω20ω20 282.81(11)278.81(8)276.74(17)285.13(16)281.84(16)278.46(13) x 11 0 -3.28(6)-3.17(8)-2.87(13)-3.58(11)-3.46(12)-3.15(11) x 22 0 0.25(2)0.26(1)0.34(3)0.28(2) 0.41(3) x 12 0 -1.55(4)-1.45(4)-1.30(9)-1.59(6)-1.54(7)-1.38(6) Emission spectra: BCl 2 ν 1 : sym stretch ν 2 : bend

16.  Fourier Transform emission study of B-X transition of BC Bernath et al, J. Chem. Phys. 93, 8482 (1990)  Matrix isolation studies of B-X and C-X transitions Maier et al, J. Phys. Chem A. 102, 9107 (1998)  LIF study of B-X system of BC (MF10) Cheung et al, Chem. Phys. Lett. 16, 509 (2011) B 4 Σ – ← X 4 Σ – 17900 cm -1 C 4 Π ← X 4 Σ – 34000 cm -1 GS: 3σ 2 4σ 2 5σ 1 1π 2 : X 4 Σ – ES: 3σ 2 4σ 1 5σ 2 1π 2 : B 4 Σ – 3σ 2 4σ 2 5σ 0 1π 2 2π 1 + 3σ 2 4σ 1 5σ 1 1π 2 2π 1 : C 4 Π Boron Carbide

17. Sync-scan LIF: B 4 Σ - ← X 4 Σ - system

18. * Feature due to 10 BC Simulated Experimental * * * * B 4 Σ - (b) ← X 4 Σ - (b) : Sync-scan LIF

19. Spin -splitting

20. a Bernath et al, J. Chem. Phys. 93, 8482 (1990) Molecular parameters Molecular Constants X4Σ–X4Σ– B4Σ–B4Σ– 11 BC 10 BC 11 BC 10 BC B0B0 1.31119(22)1.37957(38)1.36811(21)1.44023(57) λ0λ0 0.0282 a -0.0050(11) r0r0 1.4963(2)1.4647(3) T 0 ( 11 BC) = 17904.8966(26) T 0 ( 10 BC) = 17906.2710(41)

21. a Bernath et al, J. Chem. Phys. 93, 8482 (1990) 3σ3σ 4σ*4σ* 5σ5σ 1π1π 3σ3σ 4σ*4σ* 5σ5σ 1π1π Molecular parameters X4Σ–X4Σ– B4Σ–B4Σ– Molecular Constants X4Σ–X4Σ– B4Σ–B4Σ– 11 BC 10 BC 11 BC 10 BC B0B0 1.31119(22)1.37957(38)1.36811(21)1.44023(57) λ0λ0 0.0282 a -0.0050(11) r0r0 1.4963(2)1.4647(3) T 0 ( 11 BC) = 17904.8966(26) T 0 ( 10 BC) = 17906.2710(41)

22. LIF spectrum: C 4 П ← X 4 Σ - system

23. Simulated Experimental C 4 П(b) ← X 4 Σ - (b) : Total LIF spectrum

24. THANK YOU!