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PEMS Staff Photo Hans Riesen

Assoc. Prof. Hans Riesen

Associate Professor
Research Coordinator, Academic Coordinator - Education Support
Lic phil nat, Dr phil nat Berne

School of Physical, Environmental and Mathematical Sciences
UNSW @ ADFA
Canberra   ACT   2600
AUSTRALIA

Phone: +61 2 6268 8679
Fax: +61 2 6268 8017
Email: h.riesen@adfa.edu.au
Location:PEMS Nth, Room 212

Research Interests:
Applications of advanced laser spectroscopies to chemical problems in the solid state, in particular to inorganic complexes. The techniques include spectral hole-burning, fluorescence line narrowing, photon-echo measurements and other coherent transient effects as well as single-molecule spectroscopy. Frequency and time domain optical storage via spectral-hole burning holography. Homogeneous linewidth as a function of the temperature, structural properties of the host and the guest, and particle size of the host. Photochemistry of transition metal complexes in the solid state. Optical properties of doped nanoparticles. X-ray storage phosphors.

Laser Spectroscopy

Biography

Hans Riesen is a graduate of the University of Berne, Switzerland. He obtained his PhD (Dr. phil.-nat.) in 1987 for research with Prof. H.U. Güdel on the optical spectroscopy of exchange coupled binuclear chromium(III) complexes. In 1987 he joined the group of Prof. E. Krausz at the Research School of Chemistry (RSC) of the Australian National University (ANU) as a post-doctoral fellow (PDF). In 1986 and in 1989 he received awards by the Swiss National Science Foundation. Following a short stay in 1989 as a PDF at the University of Berne, he took up a position of a Research Fellow (RF) at the RSC in 1990. In 1992 he was awarded an 5-year ARC Research Fellowship. In 1994 year he was promoted to Fellow (Academic Level C) by ANU. In 1998 he joined the University College as a Lecturer. In 2000 and 2004 he was promoted to Senior Lecturer and Associate Professor, respectively. Hans Riesen has pioneered the application of advanced laser spectroscopies to inorganic complexes. In recent years he also pioneered the application of inexpensive diode lasers in this field. His present research interest builds on his long-standing experience in this fascinating field. He is particularly interested in light-induced changes in the solid state (spectral hole-burning etc) which have a potential in applications such as ultra-high density (>100000 Gigabyte/cm3) optical storage. He is the author of about 100 research articles which include two book chapters and several reviews.

Teaching
  • Chemistry 1
  • Physical Chemistry 2
  • Physical Chemistry 3
  • Bioinorganic Chemistry
  • Introduction to Engineering Materials for Electrical Engineers
Research

There are two main research themes that are currently pursued:

1. High-resolution laser spectroscopy of coordination compounds: science and applications.

The applications of very high resolution laser techniques, such as spectral hole-burning, in the spectroscopy of coordination compounds, and inorganic materials in general, are pursued. These studies provide an insight into subtle details of the electronic structure of materials. We are vigorously searching for materials that can be used in extremely high-density (>100000 Gigabytes/cm3) optical data storage and other applications such as laser stabilization schemes, portable frequency standards etc.

  • The requirement of liquid helium temperatures has so far limited the widespread application of ultra-high density optical data storage (>100000 Gigabytes/cm3) devices based on spectral hole-burning. We aim to achieve higher operating temperatures by exploiting our recent discovery of an astounding increase (~1000x) in the efficiency of non-photochemical spectral hole-burning in crystalline chromium(III) doped NaMgAl(oxalate)3.9H2O upon partial deuteration of lattice water molecules, with the effect vanishing on complete deuteration. The effect is based on photoinduced 180o flip motions of the partially deuterated water molecules of crystallization.

  • We have started to undertake optically detected NMR (ODNMR) spectroscopy, such as hole-burning ODNMR and photon echo nuclear double resonance (PENDOR) on coordination compounds.

2. Novel X-ray storage phosphors and their applications in medical imaging and personal radiation monitoring.

Latent images result in certain materials upon the exposure to X-ray irradiation. The storage mechanism is usually based on the creation of metastable electron-hole pairs. With Dr Kaczmarek I have discovered an extremely efficient X-ray storage phosphor. This phosphor may be used in medical imaging, minimizing the harmful exposure to X-rays (which can cause cancer). The phosphor shows a remarkable efficiency, the image is persistent, but can be reversibly bleached, and the resolution is unprecedented due to the small grain size. We have lodged a international patent application and are currently optimizing the specifications for this novel phosphor family.

Further topics of interest include:

Possible PhD projects include:

1. Systematic studies of dephasing processes and host-guest interactions in coordination compounds. In order to gain a better understanding of the dependence of dephasing processes on the structural properties of the guest and the host, the temperature dependence of the homogeneous linewidth of transition metal and rare earth complexes will be studied in a range of hosts.

2. Optically detected NMR in coordinaton compounds. This project has a significant potential to overcome the shortcomings of conventional NMR spectroscopy of coordination compounds with paramagnetic centres.

3. Optimising the properties of novel X-rays storage phosphors. This project would take advantage of our recent discovery of a highly effetive X-ray storage phosphor.

If you are interested in a PhD or Masters by Research in Laser Spectroscopy:
Contact: Associate Professor Hans Riesen, h.riesen@adfa.edu.au

Further information concerning scholarships at: http://www.unsw.adfa.edu.au/pems/student/pgrescourses.html

Pictures of Dr Riesen's labs:
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Staff
  • Thomas Monks-Corrigan, Honours Student
  • Tracy Massil, Research Assistant
  • Zhiqiang Liu, PhD student
Research Collaborators
  • Emeritus Prof. S. Campbell (PEMS, UNSW@ADFA)
  • Prof. D. Gamelin (Department of Chemistry, University of Washington, Seattle, USA )
  • Prof. J. M. Harrowfield (University of Strasbourg, France )
  • Prof. A. Hauser (University of Geneva, Switzerland )
  • Emeritus Prof. W. G. Jackson (PEMS, UNSW@ADFA)
  • Prof. E. Krausz (The Australian National University, Canberra)
  • Prof. N. B. Manson (The Australian National University, Canberra)
  • Prof. M. Mizuno (Kanazawa University, Japan
  • Prof. A. D. Rae (Research School of Chemistry, The Australian National University)
  • Assoc. Prof. M. Riley (University of Queensland, Brisbane)
  • Assoc. Prof. M. Stevens-Kalceff (School of Physics, UNSW, Sydney)
  • Dr A. Szabo (National Research Council of Canada - originator of modern laser spectroscopy of the solid state including FLN and hole-burning spectroscopy)
Consultancy
  • Reviewing articles for many international journals, including The Journal of Physical Chemistry, Physical Chemistry Chemical Physics, Inorganic Chemistry etc.
  • Member of the editorial board of Asian Chemistry Letters, Open Inorganic Chemistry Journal, International Journal of Spectroscopy
  • Review of theses
  • Consultant for Dosimetry & Imaging Pty Ltd.
Selected Publications

    1. Riesen, H., Güdel, H.U., 1987, Exchange interactions in a trigonal chromium(III) pair. Optical spectroscopy of tris-(?-hydroxo)-bis-[(1,4,7-trimethyl-1,4,7-triazacyclononane) chromium(III)] triperchlorate. Molecular Physics 60 (6) 1221-1244.

    2. Riesen, H., Güdel, H.U., 1987, Effect of high pressure on the exchange interactions in binuclear chromium(III) complexes. The Journal of Chemical Physics 87 (5) 3166-3172.

    3. Riesen, H., Krausz, E., 1993, Stark-swept transient hole-burning and resonant luminescence line narrowing in [Zn(bpy)3](ClO4)2:Ru(II). Chemical Physics Letters 212 (3,4) 347-352.

    4. Riesen, H., Krausz, E., 1993, Luminescence and excitation line narrowing of [Ru(2,2'-bipyridine)3-x(2,2'-bipyridine-d8)x]2+ (x=0-3) in [Zn(2,2'-bipyridine)3](ClO3)2. Unequivocal evidence for localized lowest-excited states. The Journal of Chemical Physics 99 (10) 7614-7618.

    5. Riesen, H., Wallace, L., Krausz, E., 2000, Probing the electronic structure of coordination compounds by transient spectral hole- burning. Applications to specifically deuterated [Ru(bpy)3]2+ complexes. Inorganic Chemistry 39, 5044-5052.

    6. Hughes, J.L., Riesen, H., 2003, Zeeman effects in transient spectral hole-burning of the R1 line of NaMgAl(oxalate)3.9H2O/Cr(III) in low magnetic fields. The Journal of Physical Chemistry A 107, 35-42.

    7. Riesen, H., Hughes, J.L., 2003, Memory of low magnetic fields in persistent spectral hole-burning of the 2E f4A2 spin-flip transition in NaMgAl(oxalate)3.9H2O:Cr(III). Chemical Physics Letters 370, 26-31.

    8. Riesen, H., Hughes, J.L., 2003, Massive enhancement of persistent spectral hole- burning in the R-lines of NaMgAl(oxalate)3.9H2O:Cr(III) by partial deuteration. Chemical Physics Letters 372, 563-568.

    9. Riesen, H., 2003, Effects of low magnetic fields in transient spectral hole-burning of the R1- line in emerald, Be3Al2Si6O18:Cr(III). Chemical Physics Letters 382, 578-585.

    10. Hayward, B.F., Riesen, H., 2005, Side-hole to anti-hole conversion in time-resolved transient spectral hole-burning of emerald: ground state level versus excited state population storage in low magnetic fields. Phys Chem Chem Phys 7, 2579-2586.

    11. Monks-Corrigan, T., Riesen, H., 2006, Host deuteration effects in non-photochemical spectral hole-burning in the R 1- line of [Cr(oxalate) 3 ] 3- in ethylene glycol/water. Chemical Physics Letters 419, 321-325.

    12. Riesen, H., 2006, Hole-burning spectroscopy of coordination compounds. Coordination Chemistry Reviews 250, 1737-1754.

    13. Riesen, H., Hayward, B., Szabo, A., 2007, Side-hole to anti-hole conversion in time-resolved spectral hole burning of ruby: Long-lived spectral holes due to ground state level population storage. Journal of Luminescence 127(2), 655-664.

Memberships