Applications of Spectroscopy in Lifetimes and States Excitation

In this collection of images sourced from Johns Hopkins University's Department of Chemistry, various aspects of spectroscopy applications in determining lifetimes for electronic and vibrational excited states are highlighted. Topics covered include transition energies, dipole moments, and decay rates for different types of excited states. Examples of fluorescence and phosphorescence lifetimes, as well as vibrational excited states in water molecules, are also showcased.

• Spectroscopy Applications
• Lifetimes
• Electronic Excited States
• Vibrational Excited States
• Transition Energy

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1. Spectroscopy applications (II) Spectroscopy applications (II) Lan Cheng Department of Chemistry The Johns Hopkins University 1

2. Lifetimes for electronic and vibrational excited states Lifetime decay rate ( Einstein A coefficient )

3. Lifetimes for electronic and vibrational excited states transition energy transition dipole moment speed of light

4. Lifetimes for electronic and vibrational excited states transition energy in cm-1 Transition dipole in Debye Decay rate in s-1

5. Example: fluorescence Lifetime for an allowed electronic excited state Typical lifetime

6. Example: phosphorescence Lifetime Typical lifetime

7. Example: phosphorescence Lifetime Typical lifetime

8. Example: phosphorescence Lifetime Typical lifetime

9. Example: Lifetime for a vibrationally excited state

10. Example: Lifetime for a vibrationally excited state

11. Example: Bending mode in water molecule Literature value 54 ms

12. Example: Symmetric Stretch mode in water Literature value 293 ms

13. Example: Asymmetric Stretch mode in water Literature value 12 ms

14. Example: Bending mode in CaOH A measured value of 720 ms from John Doyle s group at Harvard

15. Lifetime for CaOH in an optical dipole trap CaOH has been successfully laser-cooled and loaded into a three- dimensional magneto-optical trap (MOT). Vilas, Hallas, Anderegg, Robichaud, Winnicki, Mitra, Doyle, Nature, 606, 70-74 (2022). CaOH has recently been further loaded into an optical dipole trap (~ 20 ?K). One important application is to demonstrate precision spectroscopy using the bending mode of linear triatomic molecules. Therefore, the lifetime for the X2?(010) state of CaOH is being measured. 15

16. Contributions to the overall lifetime Spontaneous decay channel Blackbody radiation induced excitations Vanhaecke, Dulieu, Mol. Phys.105, 1723 (2007). Raman scattering from the trapping laser Vacuum loss 16

17. Computed lifetime for the X2?(010) states Unit: ms Spontaneous lifetime Molecules Theory Measured CaOH 876 720(+250,-130) SrOH 902 -- YbOH 1020 -- Measured value from John Doyle s group 17

18. Computed lifetime for the X2?(010) states Unit: ms Overall lifetime at 300K Molecules Theory Measured CaOH 409 360(+110,-70) SrOH 439 -- YbOH 440 -- Experiments with coherence times 1s are achievable provided that technical sources of loss are addressed. Measured value from John Doyle s group 18