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Observation of vibrational overtones by single-molecule resonant photodissociation.

Khanyile NB, Shu G, Brown KR - Nat Commun (2015)

Bottom Line: Here we show that this same system can be coupled with a broadband laser to discover new molecular transitions.On the basis of theoretical calculations, we assign the observed peaks to the transition from the ground vibrational state, ν=0 to ν=9 and 10.Our method allows us to track single-molecular events, and it can be extended to work with any molecule by using normal mode frequency shifts to detect the dissociation.

View Article: PubMed Central - PubMed

Affiliation: Schools of Chemistry and Biochemistry, Computational Science and Engineering, and Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.

ABSTRACT
Molecular ions can be held in a chain of laser-cooled atomic ions by sympathetic cooling. This system is ideal for performing high-precision molecular spectroscopy with applications in astrochemistry and fundamental physics. Here we show that this same system can be coupled with a broadband laser to discover new molecular transitions. We use three-ion chains of Ca(+) and CaH(+) to observe vibrational transitions via resonance-enhanced multiphoton dissociation detected by Ca(+) fluorescence. On the basis of theoretical calculations, we assign the observed peaks to the transition from the ground vibrational state, ν=0 to ν=9 and 10. Our method allows us to track single-molecular events, and it can be extended to work with any molecule by using normal mode frequency shifts to detect the dissociation. This survey spectroscopy serves as a bridge to the precision spectroscopy required for molecular ion control.

No MeSH data available.


Related in: MedlinePlus

Energy level diagram of CaH+.Simplified CaH+ energy level diagram showing the overtones excited by a pulsed, tunable infrared laser (800–900 nm). A second ultraviolet laser (377 nm) excites the overtones to the unbound state to dissociate the molecule.
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f1: Energy level diagram of CaH+.Simplified CaH+ energy level diagram showing the overtones excited by a pulsed, tunable infrared laser (800–900 nm). A second ultraviolet laser (377 nm) excites the overtones to the unbound state to dissociate the molecule.

Mentions: A 40CaH+ molecule is produced by leaking ∼5 × 10−7 Pa of molecular H2 into the chamber via a leak valve. The 40CaH+ is produced via reactive collisions in the gas phase between 40Ca+(4P1/2) and the H2 as 40Ca++H2→40CaH++H. The product molecule quickly relaxes to its electronic ground state X 1Σ+ (Fig. 1) and the motion of the molecule is sympathetically cooled by the two Ca+ ions. The occurrence of a reaction is determined when one of the ions goes dark and there is a drop in fluorescence counts. Once a reaction occurs, the leak valve is closed and the experiment is delayed until the base pressure is reached. The identity of the molecule can be determined by resolved sideband spectroscopy19, and under these experimental conditions we have only observed the formation of CaH+.


Observation of vibrational overtones by single-molecule resonant photodissociation.

Khanyile NB, Shu G, Brown KR - Nat Commun (2015)

Energy level diagram of CaH+.Simplified CaH+ energy level diagram showing the overtones excited by a pulsed, tunable infrared laser (800–900 nm). A second ultraviolet laser (377 nm) excites the overtones to the unbound state to dissociate the molecule.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525170&req=5

f1: Energy level diagram of CaH+.Simplified CaH+ energy level diagram showing the overtones excited by a pulsed, tunable infrared laser (800–900 nm). A second ultraviolet laser (377 nm) excites the overtones to the unbound state to dissociate the molecule.
Mentions: A 40CaH+ molecule is produced by leaking ∼5 × 10−7 Pa of molecular H2 into the chamber via a leak valve. The 40CaH+ is produced via reactive collisions in the gas phase between 40Ca+(4P1/2) and the H2 as 40Ca++H2→40CaH++H. The product molecule quickly relaxes to its electronic ground state X 1Σ+ (Fig. 1) and the motion of the molecule is sympathetically cooled by the two Ca+ ions. The occurrence of a reaction is determined when one of the ions goes dark and there is a drop in fluorescence counts. Once a reaction occurs, the leak valve is closed and the experiment is delayed until the base pressure is reached. The identity of the molecule can be determined by resolved sideband spectroscopy19, and under these experimental conditions we have only observed the formation of CaH+.

Bottom Line: Here we show that this same system can be coupled with a broadband laser to discover new molecular transitions.On the basis of theoretical calculations, we assign the observed peaks to the transition from the ground vibrational state, ν=0 to ν=9 and 10.Our method allows us to track single-molecular events, and it can be extended to work with any molecule by using normal mode frequency shifts to detect the dissociation.

View Article: PubMed Central - PubMed

Affiliation: Schools of Chemistry and Biochemistry, Computational Science and Engineering, and Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.

ABSTRACT
Molecular ions can be held in a chain of laser-cooled atomic ions by sympathetic cooling. This system is ideal for performing high-precision molecular spectroscopy with applications in astrochemistry and fundamental physics. Here we show that this same system can be coupled with a broadband laser to discover new molecular transitions. We use three-ion chains of Ca(+) and CaH(+) to observe vibrational transitions via resonance-enhanced multiphoton dissociation detected by Ca(+) fluorescence. On the basis of theoretical calculations, we assign the observed peaks to the transition from the ground vibrational state, ν=0 to ν=9 and 10. Our method allows us to track single-molecular events, and it can be extended to work with any molecule by using normal mode frequency shifts to detect the dissociation. This survey spectroscopy serves as a bridge to the precision spectroscopy required for molecular ion control.

No MeSH data available.


Related in: MedlinePlus