School of Physical, Environmental and Mathematical Sciences

Professor Hans Riesen

Professor
Lic phil nat, Dr phil nat Berne

Telephone: +61 2 6268 8679
Fax: +61 2 6268 88786 8017
Email: h.riesen@adfa.edu.au
Location: PEMS Nth, Room 212

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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.

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. 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.

Teaching

• Physical Chemistry 3

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 180^o 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. 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:

• Optical data storage materials
  
• Materials for laser stabilization schemes and portable frequency standards
  
• Massive enhancement of electronic spectral hole-burning by partial deuteration of lattice water molecules
  
• Water flips in inorganic hydrates probed by low temperature solid state dueterium NMR
  
• Enhanced hole-burning properties in exchange coupled systems
  
• Spectral diffusion and optical line widths in coordination compounds. Nephelauxetic versus ligand field effects
  
• Persistent memory of (low) magnetic fields
  
• Direct measurement of spin-lattice and cross relaxation in the ground and excited state by transient spectral hole-burning experiments
  
• Spectral hole-burning studies of impurities in ring and chain silicates
  
• Diode lasers in single molecule spectroscopy
  
• Optical properties of oxide nanoparticles
  
• High efficiency X-ray storage phosphor based on nanoparticles

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: Professor Hans Riesen, h.riesen@adfa.edu.au

Further information concerning scholarships at:

Pictures of Professor Riesen's labs:

Staff

• Zhiqiang Liu, PhD student
• Baran Yildirim, PhD student
• Xianglei Wang, PhD student
• Rajitha Papukutty Rajan, PhD student

Research Collaborators

• Emeritus Prof. S. Campbell (PEMS, UNSW@ADFA)
• 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. A. D. Rae (Research School of Chemistry, The Australian National University)
• 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)
• Professor Aleksander Rebane, Montana State University, USA.

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

Selected Publications

1. 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), pp. 19039-19049.
2. 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, Available from: http://www.intechopen.com/books/current-topics-in-ionizing-radiation-research/optical-storage-phosphors-and-materials-for-ionizing-radiation
3. 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), pp 8322–8331.
4. 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), pp. 241-244
5. Riesen, H., 2011, Photoinduced Electron Transfer and Persistent Spectral Hole-Burning in Natural Emerald , The Journal of Physical Chemistry A 115, 5364-5370.
6. 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.
7. 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.
   
8. 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.
9. 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.
   
10. 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.
11. 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.
    
12. 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.
13. 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.
    
14. 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.
    
15. 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.
    
16. 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.
    
17. 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.
    
18. 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.
    
19. 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.
    
20. Riesen, H., 2006, Hole-burning spectroscopy of coordination compounds, Coordination Chemistry Reviews 250, 1737-1754.
    
21. 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.
    
22. 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.
    
23. 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.
    
24. 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.
    
25. 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.
    
26. 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.
    
27. Riesen, H., 2004, Progress in hole-burning spectroscopy of coordination compounds, Structure and Bonding, 107, 179-205.
    
28. 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.
    
29. 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.
    
30. 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.
    
31. 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.
    

Memberships

• Member of the Optical Society of America