School of Physical, Environmental and Mathematical Sciences

Hans Riesen

Professor Hans Riesen


Associate Dean (Research)


Lic phil nat, Dr phil nat Berne

Telephone: +61 2 6268 8679
Fax: +61 2 6268 88786 8017
Location: PEMS Nth, Room 212

My UNSW Research Gateway Profile

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.

Functional Materials - Condensed Matter and Materials Physics


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. Guedel 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 a 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, 2004, and 2011 he was promoted to Senior Lecturer, Associate Professor and 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 120 research articles which include two book chapters and several reviews.



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.

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. We 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 are currently optimizing the specifications for this novel phosphor family and associated reader technologies.


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 effective X-ray storage phosphor.

If you are interested in a PhD or Masters by Research in Laser Spectroscopy:
Contact: Professor Hans Riesen,

Further information concerning scholarships at:

Pictures of Professor Riesen's labs:

Lab 1 Lab 2Lab 3Hans in lab Lab 4 Lab 5


Research Collaborators


Selected Publications

  1. Carceller, I., Hutchison, W.D., Riesen, H.A., 2013, Temperature dependence of the chromium(III) R1 linewidth in emereld, Chemical Physics Letters, 564, 33-36, doi: 10.1016/j.cplett.2013.02.009.
  2. Yildirim, B., Riesen, H.A., 2013, Coordination and oxidation state analysis of cobalt in nanocrystalline LiGa5O8 by X-ray absorption spectroscopy, in: Journal of Physics: Conference series, IOP Publishing, UK, pp. 1-4, presented at 15th International Conference on X-ray Absorption Fine Structure (XAFS15), Beijing, China, 22- 28 July 2012, doi: 10.1088/1742-6596/430/1/012011.
  3. Stevens-Kalceff, M.A., Liu, Z., & Riesen, H.A., 2012, Cathodoluminescence microanalysis of irradiated microcrystalline and nanocrystalline samarium doped BaFCl, Microscopy and Microanalysis, 18(6), 1229-1238, doi: 10.1017/S1431927612001559.
  4. Riesen, H. Rebane, A., Szabo, A., Carceller, I., 2012, Slowing light down by low magnetic fields: Pulse delay by transient spectral hole-burning in ruby, Optics Express, 20(17), 19039-19049, doi: 10.1364/OE.20.019039.
  5. Riesen, H., Liu, Z., 2012, Optical storage phosphors and materials for ionizing radiation, in: Current Topics in Ionizing Radiation Research, Mitsuru Nenoi (Ed.), ISBN: 978-953-51-0196-3, Intech, Rijeka, Croatia, pp. 625-648. Available from:
  6. Liu, Z., Stevens-Kalceff, M., Riesen, H., 2012, Photoluminescence and cathodoluminescence properties of nanocrystalline BaFCl:Sm3+ X-ray storage phosphor, The Journal of Physical Chemistry C, 116(14), 8322-8331, doi: 10.1021/jp301338b.
  7. Riesen, H., Monks-Corrigan, T., Manson, N.B., 2011, Temperature dependence of the R1 linewidth in Al2O3:Mn4+: A spectral hole-burning and FLN study, Chemical Physics Letters, 515(4-6), 241-244, doi: 10.1016/j.cplett.2011.09.039.
  8. Riesen, H., 2011, Photoinduced electron transfer and persistent spectral hole-burning in natural emerald, The Journal of Physical Chemistry A,, 115(21), 5364-5370, doi: 10.1021/jp2021769.
  9. Liu, Z., Massil, T., Riesen, H., 2010, Spectral hole-burning properties of Sm2+ ions generated by X-rays in BaFCl: Sm3+ nanocrystals, Physics Procedia, 3,(4),1539-1545, doi:10.1016/j.phpro.2010.01.218. Proceedings of the Tenth International Meeting on Hole Burning, Single Molecule and Related Spectroscopies: Science and Applications-HBSM 2009.
  10. Riesen, H.A., Badek, K., & Stevens-Kalceff, M.A., 2010, Correlation between inhomogeneous width and crystallite size: 2E->4a2 luminescence of Co(II) in nanocrystalline ZnAl2O4/Co(II), Chemical Physics Letters, 501(1-3), 103-107, doi:10.1016/j.cplett.2010.10.03.
  11. Riesen, H., Sellars, M., Manson, N., 2010, Preface, Physics Procedia, 3,(4), 1521-1523, doi:10.1016/j.phpro.2010.01.215. Proceedings of the Tenth International Meeting on Hole Burning, Single Molecule and Related Spectroscopies: Science and Applications-HBSM 2009.
  12. Riesen, H.A., & Szabo, A., 2010, Revisiting the temperature dependence of the homogeneous R1 linewidth in ruby, Chemical Physics Letters, 484(4-6), 181-184, doi:10.1016/j.cplett.2009.11.017.
  13. Riesen, H.A., & Szabo, A., 2010, Probing hyperfine interactions in 53Cr(III) doped Al2O3 by spectral hole-burning in low magnetic fields, Physics Procedia, 3,(4), 1577-1582, doi:10.1016/j.phpro.2010.01.224. Proceedings of the Tenth International Meeting on Hole Burning, Single Molecule and Related Spectroscopies: Science and Applications-HBSM 2009.
  14. Riesen, H.A. & Yildirim, B., 2010, Persistent spectral hole-burning in diffuse reflection: application to nanocrystalline LiGa5O8:Co2+, Journal of Physical Chemistry Letters, 1(15), 2380-2384, doi:10.1021/jz100806d.
  15. Yildirim, B., Riesen, H., 2010, Spectral hole-burning properties of LiGa5O8:Co2+ nanocrystallites, Physics Procedia, 3,(4), 1547-1551, 10.1016/j.phpro.2010.01.219. Proceedings of the Tenth International Meeting on Hole Burning, Single Molecule and Related Spectroscopies: Science and Applications-HBSM 2009.
  16. Riesen, H.A., Riesen, N., Schubert, N.B. & Szabo, A.M., 2009, Transient spectral hole-burning studies of the R2 line in ruby, Chemical Physics Letters, 475(1-3), 10-14, doi:10.1016/j.cplett.2009.04.074.
  17. Riesen, H., 2008, On the 6A1 <- 4T1 luminescence of Fe3+ in disordered nanocrystalline LiGa5O8 prepared by a combustion reaction, Chemical Physics Letters, 461(4-6), 218-221.
  18. Riesen, H., Dubicki, L., 2008, Probing the R Lines in Tris(acetylacetonato) Chromium(III) and Tris(3-bromo-acetylacetonato) Chromium(III) by luminescence and excitation line narrowing spectroscopy, Journal of Physical Chemistry A, 112(41), 10287-10293.
  19. Riesen, H., Rae, A.D., 2008, Revisiting the crystal structure and thermal properties of NaMgAl(oxalate)3 · 9H2O/Cr(III): An extraordinary spectral hole-burning material, Journal of the Royal Chemical Society, Dalton Transactions, 35, 4717-4722.
  20. Riesen, H., Kaczmarek, W.A., 2007, Efficient x-ray generation of Sm2+ in nanocrystalline BaFCl/Sm3+: A Photoluminescent x-ray storage phosphor, Inorganic Chemistry, 46(18), 7235-7237.
  21. 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.
  22. 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.
  23. Riesen, H., 2006, Hole-burning spectroscopy of coordination compounds, Coordination Chemistry Reviews 250, 1737-1754.
  24. Kaczmarek, W.A., Riesen, H., 2006, Structural and morphological properties of RE3+ doped sesquioxide Y2O3 spherical nanoparticles, Journal of Materials Science, 41(24), 8320-8328.
  25. 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.
  26. Hughes, J.L., Krausz, E., Smith, P.J., Pace, R.J., Riesen, H., 2005, Probing the lowest energy chlorophyll a states of Photosystem II via selective spectroscopy: new insights on P680, Photosynthesis Research, 84(1-3), 93-98.
  27. Hughes, J.L., Prince, B.J., Arskold, S.P., Smith, P.J., Pace, R.J., Riesen, H., Krausz, E., 2004, The native reaction centre of Photosystem II: A new paradign for P680, Australian Journal of Chemistry, 57(12), 1179-1183.
  28. Hughes, J.L., Prince, B.J., Krausz, E., Smith, P.J., Pace, R.J., Riesen, H., 2004, Highly efficient spectral hole-burning in oxygen-evolving photosystemII preparations, Journal of Physical Chemistry B, 108(29), 10428-10439.
  29. Riesen, H., 2004, Narrow spectral holes in a concentrated binuclear chromium(III) compound: studies of the 2E4A2<- 4A42A2 transition in single crystals of [LCr(III)([mu]-OH)3Cr(III)L](ClO4)3 · H2O (L=1,4,7-trimethyl-1,4,7-triazacyclononane), Chemical Physics Letters, 383(5-6), 512-517.
  30. Riesen, H., 2004, Progress in hole-burning spectroscopy of coordination compounds, Structure and Bonding, 107, 179-205.
  31. 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.
  32. 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.
  33. 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.
  34. 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.