Quantitative theoretical analysis of lifetimes and decay rates relevant in laser cooling BaH

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Abstract

Tiny radiative losses below the 0.1% level can prove ruinous to the effective laser cooling of a molecule. In this paper the laser cooling of a hydride is studied with rovibronic detail using ab initio quantum chemistry in order to document the decays to all possible electronic states (not just the vibrational branching within a single electronic transition) and to identify the most populated final quantum states. The effect of spin-orbit and associated couplings on the properties of the lowest excited states of BaH are analysed in detail. The lifetimes of the A21=2, H23=2 and E21=2 states are calculated (136 ns, 5.8 s and 46 ns respectively)for the first time, while the theoretical value for B2+1=2 is in good agreement with experiments. Using a simple rate model the numbers of absorption-emission cycles possible for both one- and two-colour cooling on the competing electronic transitions are determined, and it is clearly demonstrated that the A2 – X2+ transition is superior to B2+ – X2+, where multiple tiny decay channels degrade its efficiency. Further possible improvements to the cooling method are proposed.
Original languageEnglish
Pages (from-to)96-106
Number of pages11
JournalJournal of Quantitative Spectroscopy & Radiative Transfer
Volume211
Early online date05 Mar 2018
DOIs
Publication statusPublished - May 2018

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Laser cooling
laser cooling
decay rates
Cooling
Color
Quantum chemistry
life (durability)
Electronic states
Chemical analysis
electronics
Excited states
Hydrides
color
cooling
Orbits
quantum chemistry
decay
Molecules
hydrides
orbits

Cite this

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title = "Quantitative theoretical analysis of lifetimes and decay rates relevant in laser cooling BaH",
abstract = "Tiny radiative losses below the 0.1{\%} level can prove ruinous to the effective laser cooling of a molecule. In this paper the laser cooling of a hydride is studied with rovibronic detail using ab initio quantum chemistry in order to document the decays to all possible electronic states (not just the vibrational branching within a single electronic transition) and to identify the most populated final quantum states. The effect of spin-orbit and associated couplings on the properties of the lowest excited states of BaH are analysed in detail. The lifetimes of the A21=2, H23=2 and E21=2 states are calculated (136 ns, 5.8 s and 46 ns respectively)for the first time, while the theoretical value for B2+1=2 is in good agreement with experiments. Using a simple rate model the numbers of absorption-emission cycles possible for both one- and two-colour cooling on the competing electronic transitions are determined, and it is clearly demonstrated that the A2 – X2+ transition is superior to B2+ – X2+, where multiple tiny decay channels degrade its efficiency. Further possible improvements to the cooling method are proposed.",
author = "Keith Moore and Lane, {Ian C.}",
year = "2018",
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doi = "10.1016/j.jqsrt.2018.03.003",
language = "English",
volume = "211",
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journal = "Journal of Quantitative Spectroscopy & Radiative Transfer",
issn = "0022-4073",
publisher = "Elsevier Limited",

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TY - JOUR

T1 - Quantitative theoretical analysis of lifetimes and decay rates relevant in laser cooling BaH

AU - Moore, Keith

AU - Lane, Ian C.

PY - 2018/5

Y1 - 2018/5

N2 - Tiny radiative losses below the 0.1% level can prove ruinous to the effective laser cooling of a molecule. In this paper the laser cooling of a hydride is studied with rovibronic detail using ab initio quantum chemistry in order to document the decays to all possible electronic states (not just the vibrational branching within a single electronic transition) and to identify the most populated final quantum states. The effect of spin-orbit and associated couplings on the properties of the lowest excited states of BaH are analysed in detail. The lifetimes of the A21=2, H23=2 and E21=2 states are calculated (136 ns, 5.8 s and 46 ns respectively)for the first time, while the theoretical value for B2+1=2 is in good agreement with experiments. Using a simple rate model the numbers of absorption-emission cycles possible for both one- and two-colour cooling on the competing electronic transitions are determined, and it is clearly demonstrated that the A2 – X2+ transition is superior to B2+ – X2+, where multiple tiny decay channels degrade its efficiency. Further possible improvements to the cooling method are proposed.

AB - Tiny radiative losses below the 0.1% level can prove ruinous to the effective laser cooling of a molecule. In this paper the laser cooling of a hydride is studied with rovibronic detail using ab initio quantum chemistry in order to document the decays to all possible electronic states (not just the vibrational branching within a single electronic transition) and to identify the most populated final quantum states. The effect of spin-orbit and associated couplings on the properties of the lowest excited states of BaH are analysed in detail. The lifetimes of the A21=2, H23=2 and E21=2 states are calculated (136 ns, 5.8 s and 46 ns respectively)for the first time, while the theoretical value for B2+1=2 is in good agreement with experiments. Using a simple rate model the numbers of absorption-emission cycles possible for both one- and two-colour cooling on the competing electronic transitions are determined, and it is clearly demonstrated that the A2 – X2+ transition is superior to B2+ – X2+, where multiple tiny decay channels degrade its efficiency. Further possible improvements to the cooling method are proposed.

U2 - 10.1016/j.jqsrt.2018.03.003

DO - 10.1016/j.jqsrt.2018.03.003

M3 - Article

VL - 211

SP - 96

EP - 106

JO - Journal of Quantitative Spectroscopy & Radiative Transfer

JF - Journal of Quantitative Spectroscopy & Radiative Transfer

SN - 0022-4073

ER -