Double Resonance Spectroscopy of Ba F Autoionizing Rydberg
Double Resonance Spectroscopy of Ba. F Autoionizing Rydberg States Timothy J. Barnum, David Grimes, Yan Zhou, Robert W. Field Department of Chemistry, MIT ISMS – 23 June 2015
Motivation • Rydberg states of highly dipolar molecules • Doubly closed shell ion-core: Ba 2+F • μ~9 D • Choice candidate for investigation by CPmm. W Spectroscopy • Dissociation limit > Ionization limit • Detailed analysis of 4. 4 ≤ n* ≤ 14. 3
Previous Observations • Fluorescence detection • Ba. F effusive oven source • Lowest accessible rotational state J=6. 5 f in C 2Π 3/2 intermediate state • 10 core-penetrating series • Several series unobservable at higher n* due to weak transition moment
Experimental Scheme D 0=48200 cm-1 IPν=1=39280 cm-1 300 μJ PROBE n*~15 -25, ν+=1, N+ IPν=0=38745 cm-1 ~18600 cm-1 0. 2% SF 6/Ar TOF C 2Π 3/2, J' ~20180 cm-1 X 2 Σ+ 10 μJ PUMP 10 m. J / 532 nm
s. R 21(1. 5) • Pump blended r. R 2(X. 5) + r. Q 21([X+1]. 5) lines for access to single J levels s. R 21(0. 5) • Strong transitions to Rydberg states with d and f character Intensity (arb. units) • Conveniently about halfway between ground state and IP • p~d mixed s. R 21(2. 5) Intermediate State: C 2Π 3/2 20184 20186 Energy (cm-1) 20188
Patterns in Spectra • Δℓ=+1 propensity rule in transitions from C 2Π to Rydberg states N 2 Σ+ J 2 Λ+ 2 Λ- N N + 1/2 N - 1/2 N - 3/2 + + - - P PQ R Case (b) J N+1 N + 1/2 + - N - 1/2 + N - 3/2 + - N-1 + + OP Q 2Λ + N + 1/2 P N -1 + N – 3/2 N -2 OP + - Case (a) N N – 1/2 PQ N N - 1/2 N + - QR Q RQ J F 1 R + - N N - 1/2 F 2 N N - + + N - 2 N - 3/2 N - 5/2 + + - - N + 1 N + 3/2 N + 1/2 2Λ
Polarization Diagnostics: Linear Excitation scheme: N” → N’=N”+1 → N Intensity ratio: Parallel/Perpendicular P R Q Case(b) → Case(b) O P R Q Case(b) → Case(a) → Case(b)
Polarization Diagnostics: Circular Excitation scheme: N” → N’=N”+1 → N Intensity ratio: Same helicity/Opposite helicity R R Q P Q O P Case(b) → Case(a) → Case(b)
Polarization Diagnostics P P R Opposite Helicity R Same Helicity
Autoionizing Spectra n*~15 n*~16 J’=9. 5 J’=8. 5 J’=7. 5 J’=6. 5 J’=5. 5 J’=4. 5 J’=3. 5 J’=2. 5 J’=1. 5
Super-complex Hamiltonian 38793 38852 38792 38851 38791 14. 94 2Δ- E - B*N(N+1) 38789 38788 14. 94 38787 2 Δ+ E - B*N(N+1) (cm-1) 38790 15. 94 2Δ- 38850 38849 38848 15. 94 2Δ+ 38847 38786 38846 38785 14. 88 2Σ+ 38784 38783 0 20 40 60 80 100 120 140 160 180 200 220 240 N(N+1) 15. 88 2Σ+ 38845 38844 0 20 40 60 80 N(N+1) 100 120 140
Core-nonpenetrating States 38789 38849 38787 14. 86 E - B*N(N+1) (cm-1) 38785 38847 2Φ 38783 38781 38779 15. 86 2Φ 38845 38843 38841 38777 38839 38775 38773 38837 0 20 40 60 80 100 120 140 N (N+1) 160 180 200 220 240 0 20 40 60 80 100 N(N+1) 120 140 160 180
Core-nonpenetrating States
Core-nonpenetrating States 38789 38787 14. 86 2Φ E - B*N(N+1) (cm-1) 38785 38783 of 38781 38779 38777 38775 38773 0 20 40 60 80 100 120 140 N (N+1) 160 180 200 220 240
Conclusions • ID-OODR on Ba. F • Extend analysis of core-penetrating Rydberg series • Isolated states → Super-complex → MQDT • Foundation for CPmm. W studies of Ba. F • Detailed analysis of core-nonpenetrating states 16
Questions?
- Slides: 16