1. High-Resolution Electronic Spectroscopy of the Ultraviolet Bands of CaO
Michael N. Sullivan*, Jacob T. Stewart†, Michael C. Heaven*
*Emory University, Dept. of Chemistry, Atlanta, GA 30322
†Connecticut College, Chemistry Department, New London, CT 06320

2. Motivation Demonstrate promise for cold molecular ions
Accurate potential energy surfaces
Need spectroscopic data
Challenges
High density of states
State interaction
1Pyka et al. Nature Comm., 4, 2291, 2013.

3. Previous Work First studied 1930’s2,3,4 Green and orange bands
Field and co-workers5,6,7
Low lying electronic states
X 1Σ+, Aˈ1∏, a3∏, b3Σ+, A1Σ+
Bernath and co-workers – experimental8,9
Khalil et al. – theoretical10,11
Ground state assignment
Pearson et al.12
UV bands
Lagerqvist,
Spectral congestion
10Khalil et al. Chem. Phys., 386, 50, 2011.

4. Experimental Setup

5. Ablation Source

6. Survey Spectra Frequency (cm-1) 30,000 30,500 31,000 31,500 32,000
32,500
33,000
Frequency (cm-1)

7. (νˈ,νˈ) Frequency (cm-1) 30,000 30,500 31,000 31,500 32,000 32,500
33,000
Frequency (cm-1)

8. 32,460
32,480
32,500
32,520

9. 32,460
32,480
32,500
32,520
Frequency (cm-1)

10. (νˈ,νˈ) ? Frequency (cm-1) 30,000 30,500 31,000 31,500 32,000 32,500
33,000
Frequency (cm-1)

11. Evidence of CaOH Interstellar clouds Low lying electronic levels
Strong ionic character
Previously observed by Pereira and Levy14
D state characterized
E and F states uncharacterized
Closed shell OH- anion, and Ca+ cation (4s unpaired electron and closed shell argon core). Low lying electronic states ionic involving promotion of unpaired electrons to excited orbitals of Ca+.
R. Pereria and D.H. Levy. J. Chem. Phys., 105, 9733, 1996.

12. Band origin – 29,869.59 cm-1 Bˈˈ- .4428 cm-1
CaO - C 1Σ+ ← X 1Σ+ (2,0)
Band origin – 29, cm-1 Bˈˈ cm-1
Bˈ cm-1
CaOH – E 2Σ+ ← X 2Σ+
Band origin – 29, cm-1
Bˈˈ cm-1
Bˈ cm-1
Dˈˈ E-7 cm-1
Dˈ E-6 cm-1
TRot~ 150K

13. Molecular Constants CaO
B State (1∏)
Vibrational Assignment ν0 Bˈ
9,0
30,299.54
0.3190
10,0
30,777.67
0.3163
11,0
31,252.21
0.3145
12,0
31,722
0.3107
13,0
32,186.54
0.3091
14,0
32,645.96
0.3081
15,0
33,101.23
0.3113
Note: Ground state rotational constants from Pearson et al.12 used in fits. Units in cm-1.

14. Molecular Constants CaO
C State (1Σ+)
Vibrational Assignment ν0 Bˈ
Perturbation
2,0
29,869.59
0.3653
3,0
30,407.28
0.3620
4,0
30,938.15
0.3546
5,0
31,461.82
0.3540
6,0
31,977.67
0.3471
6,1
31,255.22
0.3497
7,0
32,496.26
0.3521 17
7,1
31,773.87
8,0
33,007.56
0.3437
8,1
32,285.11
0.3418
Note: Ground state rotational constants from Pearson et al.12 used in fits. Units in cm-1.

15. Molecular Constants CaO
D State (1Σ+)
Vibrational Assignment ν0 Bˈ
Perturbation
0,0
32,036.99
0.3159
1,0
32,496.7
0.3087 17
1,1
31,774.32
2,0
32,955.18
0.3128
Note: Ground state rotational constants from Pearson et al.12 used in fits. Units in cm-1.

16. Summary Conclusions Future Work
Investigate neutral CaO using jet cooled techniques
Extract rovibrational constants for B←X and C←X electronic bands
Observed D←X band for the first time
Future Work
Assign transitions for E←X and F←X electronic band of CaOH
Improved ablation source design
Use experimental setup to performance double resonance microwave/millimeter studies of CaO

17. Acknowledgements Dr. Michael Heaven Dr. Jacob Stewart
Dr. Adrian Gardner
Cody Anderson
Heaven group
Dr. Jiande Han
Kyle Mascaritolo
Joshua Bartlett
Robert VanGundy
Amanda Dermer

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