Ultrafast cation-dication dynamics in ammonia borane: H-migration to roaming H2 and reduced H3+ formation under strong-field ionization

Fuente: arXiv
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Autori principali: Kwon, Sung, Katturi, Naga Krishnakanth, Moreno, Bruno I., Cárdenas, Carlos, Dantus, Marcos
Natura: Preprint
Pubblicazione: 2026
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author Kwon, Sung
Katturi, Naga Krishnakanth
Moreno, Bruno I.
Cárdenas, Carlos
Dantus, Marcos
author_facet Kwon, Sung
Katturi, Naga Krishnakanth
Moreno, Bruno I.
Cárdenas, Carlos
Dantus, Marcos
contents We report a femtosecond time-resolved strong-field study of ammonia borane (AB, BH3NH3) following both single and double ionization, revealing ultrafast fragmentation dynamics and hydrogen release. Mass spectrometry, combined with fragment correlation analysis and ab initio molecular dynamics simulations, is used to identify the molecular origin of the neutral and ionic products. Singly ionized AB produces neutral H and H2, while doubly ionized AB produces neutral H and H2 along with H+, H2+, and H3+, all within 1 ps. Electronic-structure calculations show that H, H+, H2, H2+, and H3+ originate predominantly from hydrogen atoms bound to the boron center and that their formation proceeds through hydrogen migration and, in some channels, neutral H2 roaming. The calculations further indicate that the dication meets the structural and energetic requirements for neutral H2 release, a prerequisite for forming astrochemically relevant H3+. However, the large adiabatic relaxation energy causes most roaming H2 to dissociate before proton abstraction, suppressing H3+ formation. These results provide new insight into dissociative ionization pathways in hydrogen-rich molecules, extend mechanistic principles developed for halogenated alkanes to ammonia borane, and suggest implications for hydrogen-release chemistry in ammonia-borane-based storage materials.
format Preprint
id arxiv_https___arxiv_org_abs_2601_02510
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Ultrafast cation-dication dynamics in ammonia borane: H-migration to roaming H2 and reduced H3+ formation under strong-field ionization
Kwon, Sung
Katturi, Naga Krishnakanth
Moreno, Bruno I.
Cárdenas, Carlos
Dantus, Marcos
Chemical Physics
We report a femtosecond time-resolved strong-field study of ammonia borane (AB, BH3NH3) following both single and double ionization, revealing ultrafast fragmentation dynamics and hydrogen release. Mass spectrometry, combined with fragment correlation analysis and ab initio molecular dynamics simulations, is used to identify the molecular origin of the neutral and ionic products. Singly ionized AB produces neutral H and H2, while doubly ionized AB produces neutral H and H2 along with H+, H2+, and H3+, all within 1 ps. Electronic-structure calculations show that H, H+, H2, H2+, and H3+ originate predominantly from hydrogen atoms bound to the boron center and that their formation proceeds through hydrogen migration and, in some channels, neutral H2 roaming. The calculations further indicate that the dication meets the structural and energetic requirements for neutral H2 release, a prerequisite for forming astrochemically relevant H3+. However, the large adiabatic relaxation energy causes most roaming H2 to dissociate before proton abstraction, suppressing H3+ formation. These results provide new insight into dissociative ionization pathways in hydrogen-rich molecules, extend mechanistic principles developed for halogenated alkanes to ammonia borane, and suggest implications for hydrogen-release chemistry in ammonia-borane-based storage materials.
title Ultrafast cation-dication dynamics in ammonia borane: H-migration to roaming H2 and reduced H3+ formation under strong-field ionization
topic Chemical Physics
url https://arxiv.org/abs/2601.02510