Measurement of the orientation of buffer-gas-cooled, electrostatically-guided ammonia molecules
The extent to which the spatial orientation of internally and translationally cold ammonia molecules can be controlled as molecules pass out of a quadrupole guide and through different electric field regions is examined. Ammonia molecules are collisionally cooled in a buffer gas cell, and are subseq...
| Main Authors: | , , , , |
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| Format: | Journal article |
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Elsevier
2016
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| _version_ | 1797068984559861760 |
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| author | Steer, E Petralia, LS Western, C Heazlewood, B Softley, T |
| author_facet | Steer, E Petralia, LS Western, C Heazlewood, B Softley, T |
| author_sort | Steer, E |
| collection | OXFORD |
| description | The extent to which the spatial orientation of internally and translationally cold ammonia molecules can be controlled as molecules pass out of a quadrupole guide and through different electric field regions is examined. Ammonia molecules are collisionally cooled in a buffer gas cell, and are subsequently guided by a three-bend electrostatic quadrupole into a detection chamber. The orientation of ammonia molecules is probed using (2+1) resonance-enhanced multiphoton ionisation (REMPI), with the laser polarisation axis aligned both parallel and perpendicular to the time-of-flight axis. Even with the presence of a near-zero field region, the ammonia REMPI spectra indicate some retention of orientation. Monte Carlo simulations propagating the time-dependent Schrödinger equation in a full basis set including the hyperfine interaction enable the orientation of ammonia molecules to be calculated – with respect to both the local field direction and a space-fixed axis – as the molecules pass through different electric field regions. The simulations indicate that the orientation of ∼95% of ammonia molecules in JK=11 could be achieved with the application of a small bias voltage (17 V) to the mesh separating the quadrupole and detection regions. Following the recent combination of the buffer gas cell and quadrupole guide apparatus with a linear Paul ion trap, this result could enable one to examine the influence of molecular orientation on ion-molecule reaction dynamics and kinetics. |
| first_indexed | 2024-03-06T22:17:55Z |
| format | Journal article |
| id | oxford-uuid:5407a3cf-fe6d-438e-807a-9f68f073bf48 |
| institution | University of Oxford |
| last_indexed | 2024-03-06T22:17:55Z |
| publishDate | 2016 |
| publisher | Elsevier |
| record_format | dspace |
| spelling | oxford-uuid:5407a3cf-fe6d-438e-807a-9f68f073bf482022-03-26T16:35:21ZMeasurement of the orientation of buffer-gas-cooled, electrostatically-guided ammonia moleculesJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:5407a3cf-fe6d-438e-807a-9f68f073bf48Symplectic Elements at OxfordElsevier2016Steer, EPetralia, LSWestern, CHeazlewood, BSoftley, TThe extent to which the spatial orientation of internally and translationally cold ammonia molecules can be controlled as molecules pass out of a quadrupole guide and through different electric field regions is examined. Ammonia molecules are collisionally cooled in a buffer gas cell, and are subsequently guided by a three-bend electrostatic quadrupole into a detection chamber. The orientation of ammonia molecules is probed using (2+1) resonance-enhanced multiphoton ionisation (REMPI), with the laser polarisation axis aligned both parallel and perpendicular to the time-of-flight axis. Even with the presence of a near-zero field region, the ammonia REMPI spectra indicate some retention of orientation. Monte Carlo simulations propagating the time-dependent Schrödinger equation in a full basis set including the hyperfine interaction enable the orientation of ammonia molecules to be calculated – with respect to both the local field direction and a space-fixed axis – as the molecules pass through different electric field regions. The simulations indicate that the orientation of ∼95% of ammonia molecules in JK=11 could be achieved with the application of a small bias voltage (17 V) to the mesh separating the quadrupole and detection regions. Following the recent combination of the buffer gas cell and quadrupole guide apparatus with a linear Paul ion trap, this result could enable one to examine the influence of molecular orientation on ion-molecule reaction dynamics and kinetics. |
| spellingShingle | Steer, E Petralia, LS Western, C Heazlewood, B Softley, T Measurement of the orientation of buffer-gas-cooled, electrostatically-guided ammonia molecules |
| title | Measurement of the orientation of buffer-gas-cooled, electrostatically-guided ammonia molecules |
| title_full | Measurement of the orientation of buffer-gas-cooled, electrostatically-guided ammonia molecules |
| title_fullStr | Measurement of the orientation of buffer-gas-cooled, electrostatically-guided ammonia molecules |
| title_full_unstemmed | Measurement of the orientation of buffer-gas-cooled, electrostatically-guided ammonia molecules |
| title_short | Measurement of the orientation of buffer-gas-cooled, electrostatically-guided ammonia molecules |
| title_sort | measurement of the orientation of buffer gas cooled electrostatically guided ammonia molecules |
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