Title: Mechanisms and dynamics of the NH⁺₂ + H⁺ and NH⁺ + H⁺ + H fragmentation channels upon single-photon double ionization of NH₃

Abstract

We present state-selective measurements on the NH$$_2^{+}$$ + H$$^{+}$$ and NH$$^{+}$$ + H$$^{+}$$ + H dissociation channels following single-photon double ionization at 61.5 eV of neutral NH$$_{3}$$, where the two photoelectrons and two cations are measured in coincidence using 3-D momentum imaging. Three dication electronic states are identified to contribute to the NH$$_2^{+}$$ + H$$^{+}$$ dissociation channel, where the excitation in one of the three states undergoes intersystem crossing prior to dissociation, producing a cold NH$$_2^+$$ fragment. In contrast, the other two states directly dissociate, producing a ro-vibrationally excited NH$$_2^+$$ fragment with roughly 1 eV of internal energy. The NH$$^{+}$$ + H$$^{+}$$ + H channel is fed by direct dissociation from three intermediate dication states, one of which is shared with the NH$$_2^{+}$$ + H$$^{+}$$ channel. We find evidence of autoionization contributing to each of the double ionization channels. Finally, the distributions of the relative emission angle between the two photoelectrons, as well as the relative angle between the recoil axis of the molecular breakup and the polarization vector of the ionizing field, are also presented to provide insight on the ionization mechanisms for the different dication states.

Authors:

Larsen, Kirk A.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-3252-260X"

Rescigno, Thomas N. ^[2]; Streeter, Zachary L. ^[3]; Iskandar, Wael ^[2]; Heck, Saijoscha ^[4]; Gatton, Averell ^[5]; Champenois, Elio G. ^[1]; Severt, Travis ^[6]; Strom, Richard ^[7]; Jochim, Bethany  ^[6];

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• Search DOE PAGES for ORCID "0000-0003-2040-1453"

Reedy, Dylan ^[8]; Call, Demitri ^[8]; Moshammer, Robert ^[9]; Dörner, Reinhard ^[10]; Landers, Allen L. ^[7]; Williams, Joshua B. ^[8]; McCurdy, C. William ^[3]; Lucchese, Robert R.  ^[2];

• Search DOE PAGES for author "Lucchese, Robert R."
• Search DOE PAGES for ORCID "0000-0002-7200-3775"

Ben-Itzhak, Itzik ^[6]; Slaughter, Daniel S.  ^[2]

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• Search DOE PAGES for ORCID "0000-0002-4621-4552"

more »; Weber, Thorsten  ^[2]

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• Search DOE PAGES for ORCID "0000-0003-3756-2704"

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+ Show Author Affiliations

1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Davis, CA (United States)
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Max Planck Inst. fur Kernphysik, Heidelberg (Germany); J.W. Goethe Univ., Frankfurt (Germany)
5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Auburn Univ., AL (United States)
6. Kansas State Univ., Manhattan, KS (United States)
7. Auburn Univ., AL (United States)
8. Univ. of Nevada, Reno, NV (United States)
9. Max Planck Inst. fur Kernphysik, Heidelberg (Germany)
10. J.W. Goethe Univ., Frankfurt (Germany)

Publication Date:

Thu Nov 19 00:00:00 EST 2020

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kansas State Univ., Manhattan, KS (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; National Science Foundation (NSF)

OSTI Identifier:

1658358

Alternate Identifier(s):

OSTI ID: 1840508

Grant/Contract Number:  

AC02-05CH11231; FG02-86ER13491; PHY-1807017

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physics. B, Atomic, Molecular and Optical Physics

Additional Journal Information:

Journal Volume: 53; Journal Issue: 24; Journal ID: ISSN 0953-4075

Publisher:

IOP Publishing

Country of Publication:

United States

Language:

English

Subject:

74 ATOMIC AND MOLECULAR PHYSICS; photoionization; photodissociation; COLTRIMS; double ionization; intersystem crossing; non-adiabatic dynamics; autoionization