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Personal profile

Research Interests

Recent advances in laser technology have facilitated the experimental analysis of atomic structure and electron dynamics in undprecedented detail. The process of harmonic generation in particular has been central to these advances both as a basis for ultrashort and high-energy laser pulses and as a tool for elucidating ultrafast dynamics. Typically, now, we are interested in dynamics which occur on the attosecond scale (1 as = 10-18 s), which is the fundamental time scale of electronic motion in the atom.

Theoretical methods capable of describing attosecond scale electronic motion typically adopt a classical approach where an electron is driven by a laser field in the net potential of the residual ion. However, methods pioneered at QUB allow us to address the interaction of all the electrons in an atomic system. It is these multielectron interactions which mediate ultrafast dynamics and thus it is imperative to address them accurately.

Time-dependent R-matrix (TDRM) theory, and the associated TDRM and RMT (R-matrix incorporating time dependence) codes, are among the only methods in the world capable of describing multielectron and multichannel effects in ultrafast laser atom interactions. For my PhD thesis I used the TDRM method to address harmonic generation-- the production of high frequency laser light via stimulated subcycle electron motion-- and uncovered a series of multielectron aspects to the process. For instance, interference bewteen electrons competing in the harmonic generation process can lead to an increase in the harmonic yield at particular frequencies.

I have since extended these studies of ultrafast processes to experimentally relevant (mid-IR) wavelengths. Now my research focuses on extracting experimental observables from the detailed ab-initio calculations performed with RMT. To this end I have investigated several cutting-edge experimental schemes using the RMT approach, including attosecond transient absorption spectroscopy, strong-field rescattering and, most recently, XUV initiated high harmonic generation.

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  • 45 Similar Profiles
harmonic generations Physics & Astronomy
pulses Physics & Astronomy
time dependence Physics & Astronomy
lasers Physics & Astronomy
electrons Physics & Astronomy
harmonics Physics & Astronomy
interference Physics & Astronomy
photodetachment Physics & Astronomy

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Projects 2017 2019

Research Output 2012 2019

Open Access
Open Access

The R-matrix with time dependence (RMT) code

Brown, A., Van Der Hart, H., Armstrong, G., Wragg, J., Clarke, D., Gorfinkiel, J., Benda, J. & Masin, Z., 11 Nov 2019

Research output: Non-textual formSoftware

time dependence
3 Citations (Scopus)
Open Access
harmonic generations
infrared lasers
1 Citation (Scopus)

On the Cooper minimum in singly ionized and neutral argon

Hassouneh, O., Tyndall, N. B., Wragg, J., Van Der Hart, H. W. & Brown, A. C., 15 Oct 2018, In : Physical Review A (Atomic, Molecular, and Optical Physics). 98, 4, 9 p., 043419.

Research output: Contribution to journalArticle

Open Access
harmonic generations
atomic structure
cross sections


Cooper Minimum in PICS and HHG spectra in Ar+

Brown, A. (Creator), Tyndall, N. (Creator), Hassouneh, O. (Creator), Queen's University Belfast, 28 Aug 2018



XUV initiated HHG in argon

Brown, A. (Creator), Queen's University Belfast, 28 Jul 2017




Best Student Poster

Andrew Brown (Recipient), 23 Jul 2011

Prize: Prize (including medals and awards)

Best Student Speaker

Andrew Brown (Recipient), 28 Jun 2012

Prize: Prize (including medals and awards)

Activities 2011 2016

  • 9 Participation in conference
  • 3 Participation in workshop, seminar, course
  • 1 Participation in Festival/Exhibition

Intel- preparing your software for Knight's Landing

Andrew Brown (Participant)
11 Feb 2016

Activity: Participating in or organising an event typesParticipation in workshop, seminar, course

AMIG: Atomic and Molecular Interactions Group

Andrew Brown (Participant)
31 May 2016

Activity: Participating in or organising an event typesParticipation in conference

Faraday discussion: Ultrafast imaging and photochemical dynamics

Andrew Brown (Participant)
31 Aug 201602 Sep 2016

Activity: Participating in or organising an event typesParticipation in conference

EU-COST Action: XLIC (XUV/X-ray light and fast ions for ultrafast chemistry)

Andrew Brown (Invited speaker)
30 Aug 2016

Activity: Participating in or organising an event typesParticipation in conference

Bothe Colloquium

Andrew Brown (Invited speaker)
13 May 2015

Activity: Participating in or organising an event typesParticipation in workshop, seminar, course

Press / Media

Mathsweek Ireland promotion 2016

Daniel Dundas & Andrew Brown


1 media contribution

Press/Media: Public Engagement Activities