1. Laser Cooling Molecules Joe Velasquez, III*, Peter L. Walstrom †, and Michael D. Di Rosa* * Chemistry Division, Physical Chemistry and Applied Spectroscopy † Accelerator Operations and Technology, AOT-ABS (LA-UR 14-24481) AOT

2. Non-Arrhenius Chemistry at Very Low T Inelastic collisions at ultra-cold temperatures may have enhanced rates!? 2  molecule and 2 S atom colliding at low temperature result in two possible total spin values: S = 1 and S = 0: CaH + Li → ?? < 1K CaH + Li LiH + Ca ↓↑ ↑↑ R.V. Krems, Cold Controlled Chemistry. PCCP. 10, 4079-4092 (2008).

3. Stark Deceleration (10s of mK) Common Cooling Techniques for molecules Photoassociation Other techniques: Buffer gas cooling, spinning nozzle velocity Input Velocity Distribution Output Velocity Distribution Laser

4. Laser Cooling Molecules Directly Molecular structure necessarily means electronic transition-cycling is inefficient! To laser cool a molecule one would like: 1.Large oscillator strength for a given one-photon transition 2.A highly diagonal Franck-Condon band 3.A clean upper electronic state with no curve-crossings  00 X-state A-state  00  01  02  0n v'' v' n 2 1 0 0

5. Molecule 00, nm 01, nm BeH499.2554.2 MgH518.7562.3 CaH693.0759.3 SrH739.4815.0 BaH10341176 NH335.8377.4 BH433.2482.6 AlH424.1457.6 AlF227.5231.8 AlCl261.5264.9 Candidate Molecules M. D. Di Rosa, Laser-cooling molecules Eur. Phys. J. D. 31, 295-402 (2004).

6. Candidate Molecules for Laser Cooling

7. Combined Beams to Instrument 2.4 m Source Zeeman Slower Cooling lasers (on beam axis) 1.25 T Dipole Experimental Frequency Monitoring Dye 1Dye 2 Diode 1 Diode 2 AOM

8. Fiber-Coupled Pulsed Laser Ablation Source Evacuated chamber Launch fiber (Ø1200-800  m) Ø1 cm Nd:YAG 2  16 m Long Fiber ( Ø 1000-800 um) In-vacuum Fiber ( Ø 800 um) Aspherical Lens Target Vacuum feedthrough Throughput approaches 60 % Could be improved through better and fewer SMA-SMA connections f/2 positive lens

9. Observed Lithium-7 Subcooling in Xe Jet

10. Laser Cooling Scheme

11. Building Density: A Page from Accelerator Physics Paramagnetic particles may experience a force in a magnetic field, The trap must have a minimum, nonzero field for the stored state, The stored state must be intrinsically different than the injected state (Liouville’s Theorem) F = ± grad (  B ) We can achieve quantum-state specificity through Optical Pumping

12. Optical Pumping of Li-7 at High Fields

13. Early Accumulator Designs Linear Trap (Solenoid/Hexapoles) “Racetrack” histogram of v r from Monte-Carlo simulation x z y Linear Trap Radial Velocity Acceptance time, sec z -coordinate, m No Stable Orbits

14. The Cusp Solenoid z x y Trapping Volume Entry Cusp Solenoid Axis ( y ), m xy Contour Plot of | B | | B | in T x -coordinate, m y -coordinate (beam axis), m | B |, T State-Switching and Trapped Extents

15. histogram of v r from Monte-Carlo simulation Acceptance Range Cusp Solenoid Linear hexapole histogram of v axial from Monte-Carlo simulation Radial Velocity Acceptance of Cusp Solenoid Radial Velocity, cm/sec Axial Velocity Acceptance of Cusp Solenoid Axial Velocity, m/sec Counts

16. xy and yz Orbit Projections for Cusp Solenoid y -coordinate (beam axis), m

17. We wish to thank the Los Alamos LDRD program for funding.