Controlling the internal excitation of H3+ produced in a duoplasmatron ion source
(2025) Journal of Physics B: Atomic, Molecular and Optical Physics — Vol. 58, n° 19, p. 195205 (2025)
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- Authors
Ivanov, Dmitry 
Bu, Caixia Hillenbrand, Pierre-Michel Schury, Daniel Savin, Daniel Wolf
- Abstract
- (en) We have explored a combination of two methods to control the internal excitation of H3+ produced in a duoplasmatron ion source. The H3+ was formed starting from a gas of H2. The first control method varied the H2 pressure in the ion source to collisionally relax any internally excited (H3+)∗. The second method added Ar to the source to chemically destroy (H3+)∗ with internal excitation energies Eint ⩾ 0.57 eV, using the endoergic reaction H3+ + Ar → ArH++H2. To infer the H3+ internal temperature, Tint, representative of internal excitation under the hypothesis of thermodynamic equilibrium, we used merged-beams rate coefficient measurements of the endoergic deuterating reaction H3+ + D → H2D + + H2 and a semi-empirical theoretical model. We found that using collisional relaxation alone, we could vary Tint over the range ≈1300 − 2200 K. Combining collisional relaxation and chemical destruction, we reduced the minimum to Tint ≈ 1130 K. Over this temperature range, the fraction of H3+ where all vibrational modes are in their v = 0 level varies from ≈0.88 at the lowest temperature to ≈0.44 at the highest temperature. This combination of cooling methods offers a otentially powerful means for studying reactive scattering processes as a function of the internal excitation of the H3+.
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Citations
Ivanov, D., Bu, C., Hillenbrand, P.-M., Schury, D., Urbain, X., & Savin, D. W. (2025). Controlling the internal excitation of H3+ produced in a duoplasmatron ion source. Journal of Physics B: Atomic, Molecular and Optical Physics, 58(19), 195205. https://doi.org/10.1088/1361-6455/ae0b16 (Original work published 2025)