Limits...
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

Dissociation measurement.After reaction with hydrogen, a mixed Coulomb crystal of two Ca+ ions and one CaH+ ion. The dissociating lasers are applied and the time to dissociation, τd, is measured by observing the change in fluorescence. The red trace shows an example dissociation event when the infrared laser is resonant with an overtone. The blue trace is an event when the infrared laser is blocked. A pinhole in the optical system allows us to correlate fluorescence with not only the number of Ca+ ions but also the relative position of the molecular ion.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4525170&req=5

f2: Dissociation measurement.After reaction with hydrogen, a mixed Coulomb crystal of two Ca+ ions and one CaH+ ion. The dissociating lasers are applied and the time to dissociation, τd, is measured by observing the change in fluorescence. The red trace shows an example dissociation event when the infrared laser is resonant with an overtone. The blue trace is an event when the infrared laser is blocked. A pinhole in the optical system allows us to correlate fluorescence with not only the number of Ca+ ions but also the relative position of the molecular ion.

Mentions: A pinhole before the photon multiplier tube allows partial light collection from all three ions and reduces background due to scattered light. Misalignment from the crystal centre results in three distinct collection efficiencies for each ion position. This allows us to detect the position of the dark ion from the fluorescence as shown in Fig. 2. The ion position shifts are due to collision with background gas. Small ion chains of any length could be used to collect the data, and test experiments were performed loading two to four Ca+ ions. Three-ion chains were preferred due to faster molecule formation time relative to two ion chains and improved stability relative to four ion chains.


Observation of vibrational overtones by single-molecule resonant photodissociation.

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

Dissociation measurement.After reaction with hydrogen, a mixed Coulomb crystal of two Ca+ ions and one CaH+ ion. The dissociating lasers are applied and the time to dissociation, τd, is measured by observing the change in fluorescence. The red trace shows an example dissociation event when the infrared laser is resonant with an overtone. The blue trace is an event when the infrared laser is blocked. A pinhole in the optical system allows us to correlate fluorescence with not only the number of Ca+ ions but also the relative position of the molecular ion.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Dissociation measurement.After reaction with hydrogen, a mixed Coulomb crystal of two Ca+ ions and one CaH+ ion. The dissociating lasers are applied and the time to dissociation, τd, is measured by observing the change in fluorescence. The red trace shows an example dissociation event when the infrared laser is resonant with an overtone. The blue trace is an event when the infrared laser is blocked. A pinhole in the optical system allows us to correlate fluorescence with not only the number of Ca+ ions but also the relative position of the molecular ion.
Mentions: A pinhole before the photon multiplier tube allows partial light collection from all three ions and reduces background due to scattered light. Misalignment from the crystal centre results in three distinct collection efficiencies for each ion position. This allows us to detect the position of the dark ion from the fluorescence as shown in Fig. 2. The ion position shifts are due to collision with background gas. Small ion chains of any length could be used to collect the data, and test experiments were performed loading two to four Ca+ ions. Three-ion chains were preferred due to faster molecule formation time relative to two ion chains and improved stability relative to four ion chains.

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