Dr H W van der Hart
(Hugo van der Hart)

• Postal address
  
• Dr H W van der Hart
  Dept of Applied Mathematics and Theoretical Physics
  David Bates Building
  Queen's University Belfast
  Belfast, BT7 1NN
  Northern Ireland
  United Kingdom
  


• Telephone +44 (0)28 9097 6048 (direct line)
• Telephone +44 (0)28 9097 6001/2 (departmental office)
• Fax +44 (0)28 9097 6061
• email h.vanderhart@qub.ac.uk
• Official homepage

• Position
• Reader in Applied Mathematics and Theoretical Physics
• Member of Centre for Theoretical Atomic Molecular and Optical Physics
• Chair of the School Safety Committee



• Location
• Room 0G.031, David Bates Building
• Telephone (internal) 6048

• The R-matrix Floquet approach for multiphoton processes
  My main interest is the theoretical study of many-electron systems embedded in strong laser fields. One of the techniques used at present is the R-matrix-Floquet approach . This approach has been developed during the 1990's and is one of the leading methods for the investigation of multiphoton processes. Recent highlights of applications of R-matrix-Floquet theory include

  • Excellent agreement with fully independent time-dependent calculations for ionization rates of He at 390 nm. Agreement is typically within 10% for a process requiring absorption of at least 9 photons.
  • Two-photon double ionization of He for photon energies between 40 and 48 eV. R-matrix Floquet theory was a pioneering technique for this process, which is now a focal point for theoretical and experimental investigation.
  • Two-photon emission of inner-shell electrons when complex atoms are irradiated by VUV (free-electron) laser light. We have studied emission of a 1s electron from Li^-. We have also established that emission of a 2s electron from Ne⁺ in the 1s²2s²2p⁵ ground state is a very important two-photon ionization process.

• Time-dependent R-matrix approach
  The R-matrix-Floquet approach can not be used to describe the response of atoms to ultra-short light fields, since it assumes the pulse to be infinitely long. We are therefore developing a time-dependent R-matrix approach. The first application of this technique was to study Ar atoms in intense few-cycle pulses. From the behaviour of the wavefunction, we were able to obtain ionization in excellent agreement with those obtained using the R-matrix-Floquet approach, thereby demonstrating the accuracy of this new technique.

• Recollision model calculations
  A different approach to investigating the behaviour of atoms in strong laser fields is through the application of model calculations. These calculations cannot provide detailed results, but they provide insight into the physics of many-electron atoms in strong laser fields.

• B-spline basis set techniques
  I am also highly interested in the development and application of B-spline techniques for atomic physics calculations. B-spline basis sets are very well suited for high-accuracy calculations. These sophisticated basis sets have been applied to study the following properties of two- and three-electron atoms :

• Energies
• Radiative lifetimes
• Autoionization lifetimes
• Electron scattering
• Photoionization
• Double photoionization
• Triple photoionization

For an overview of research publications, please visit my official homepage.

• Undergraduate courses:
• AMA320: Investigations
• AMA401: Theoretical Atomic Structure and Collisions



• Ph.D. students
• B-spline basis sets and their application to the Schrödinger equation