The research interests of Roman Krahne are centered on the optical and electronic properties of nanostructures, in particular on colloidal semiconductor nanocrystals, as well as on organic and bio-molecules. One focus is on transport experiments on single nanostructures and the development of techniques to contact individual nanoparticles. In this respect he worked with electrostatic trapping, electron-beam overlayer lithography and surface functionalization. The range of mesoscopic systems that can be probed by these approaches spans from metal, magnetic, and semiconductor nanocrystals to single organic molecules and proteins. Another main activity of his research is the assembly of shape-controlled nanocrystals into ordered arrays and the optical characterization of these systems. He developed electric-field mediated alignment approaches to fabricate oriented arrays of nanorods and characterized their optical and phonon excitations by photoluminescence and Raman spectroscopy. Roman Krahne has great experience in top-down fabrication of nanostructures by semiconductor technology. He prepared large scale, field effect-induced, quantum dot arrays in GaAs/AlGaAs based systems for far-infrared and Raman studies, and developed new device structures for nanoscale electrode gaps based on optical lithography, where the gap size is determined by the sub-nanometer precision of molecular-beam epitaxy.

1. Anna Persano, Milena De Giorgi, Angela Fiore, Roberto Cingolani, Liberato Manna, Adriano Cola and Roman Krahne, „ Photoconduction Properties in Aligned Assemblies of Colloidal CdSe/CdS Nanorods, ACS Nano 4 (3), pp 1646–1652 (2010), DOI: 10.1021/nn901575r
2. Margherita Zavelani-Rossi, Maria Grazia Lupo, Roman Krahne, Liberato Manna, Guglielmo Lanzani, “Lasing in self assembled microcavities of colloidal core/shell CdSe/CdS quantum rods”, Nanoscale (2010), DOI: 10.1039/b9nr00434c
3. Roman Krahne and Liberato Manna. “Colloidal Inorganic Nanocrystals: Synthesis and Controlled Assembly”, Handbook of Nanofabrication, edited by Stefano Cabrini, C&C Press – Taylor and Francis (2010), in press
4. Roman Krahne and Liberato Manna. “Tetrapod-shaped semiconductor nanocrystals”, Handbook of Nanophysics, edited by Klaus Sattler, C&C Press – Taylor and Francis (2010), in press
5. Dirk Dorfs, Roman Krahne, Cinzia Giannini, Andrea Falqui, Daniela Zanchet and Liberato Manna, “Synthesis and characterization of quantum dots”. Comprehensive Nanoscience and Technology, Edited by David Andrews, Greg Scholes and Gary Wiederrecht, Elsevier, in press
6. G. Maruccio, E. Primiceri, P. Marzo, V. Arima, T. Pellegrino, R. Krahne, A. Della Torre, R. Cingolani and R. Rinaldi, “A nanoelectrode-based biosensor for the detection of single biorecognition events.” Analyst 134, 2458-2461 (2009)
7. C. Nobile, L. Carbone, A. Fiore, R. Cingolani, L. Manna, and R. Krahne, “Self assembly of highly fluorescent semiconductor nanorods into large scale smectic liquid crystal phases by externally stimulated evaporation dynamics.”  J. Phys.: Condens. Matter 21 264013 (2009)
8. C. Nobile, P.l D. Ashby, P. J. Schuck, A. Fiore, R. Mastria, R. Cingolani,  L. Manna, and R. Krahne. "Probe tips functionalized with colloidal nanocrystal tetrapods for high resolution atomic force microscopy imaging." Small 4 (12), 2123-21-26 (2008)
9. L. Carbone, C. Nobile, M. De Giorgi, F. Della Sala, G. Morello, P. Pompa, M. Hytch, E. Snoeck, A. Fiore, I. R. Franchini, M. Nadasan, A. F. Silvestre, L. Chiodo, S. Kudera, R. Cingolani, R. Krahne, and L. Manna,

10.  Synthesis and micrometer-scale assembly of colloidal CdSe/CdS nanorods prepared by a seeded growth approach, Nano Letters 7 (10), 2942-2950  (2007) DOI: 10.1021/nl0717661

11.  G. Maruccio, P. Marzo, R. Krahne, A. Passaseo, R. Cingolani, and R. Rinaldi, Protein conduction and negative differential resistance in large-scale nanojunction arrays, Small 3(7),  1184-1188 (2007) DOI: 10.1002/smll.200600600

12.  G. Maruccio , P. Marzo, R. Krahne, A. Della Torre, A. Passaseo, R. Cingolani, R. Rinaldi,, Fabrication and transport of large-scale molecular tunnel-junction arrays, Microelectronic Engineering 84(5-8), 1585-1588 (2007), DOI:10.1016/j.mee.2007.01.107

13.  A. Della Torre, P.P. Pompa, L.L. del Mercato, R. Chiuri, R. Krahne, G. Maruccio, L. Carbone, L. Manna, R. Cingolani, and R. Rinaldi, Interconnection of specific nano-objects by electron beam lithography – a controllable method, Materials Science and Engineering 28 (2), 299-302 (2008), DOI: 10.1016/j.msec.2007.01.009

14.  C. Nobile, V. A. Fonoberov, S. Kudera, A. Della Torre, A. Ruffino, G. Chilla, T. Kipp, D. Heitmann, R. Cingolani, L. Manna, A.A. Balandin, and R. Krahne, Confined optical phonon modes in aligned nanorod arrays detected by resonant inelastic light scattering, Nano Letters 7 (2), 476-479 (2007) DOI: 10.1021/nl062818+

15.  C. Nobile, S. Kudera, A. Fiore, L. Carbone, G. Chilla, T. Kipp, D. Heitmann, R. Cingolani, L. Manna, and R. Krahne, Confinement effects on optical phonons in spherical, rod-, and tetrapod-shaped nanocrystals detected by Raman spectroscopy, phys. Stat. Sol. (a) 204, No. 2, 483–486 (2007) / DOI 10.1002/pssa.200673223

16.  R. Krahne, G. Chilla,  Ch. Schűller, L. Carbone, S. Kudera, D. Tarì, M. DeGiorgi, D. Heitmann, R. Cingolani, L. Manna,, Shape dependence of the scattering processes of optical phonons in colloidal nanocrystals detected by Raman spectroscopy,, Journal of Nanoelectronics and Optoelectronics 1 (1), 104-107 (2006).DOI  10.1166/jno.2006.012

17.  R. Krahne, G. Chilla,  Ch. Schűller, L. Carbone, S. Kudera, G. Mannarini, L. Manna, D. Heitmann, R. Cingolani, Confinement effects on optical phonons in polar tetrapod nanocrystals detected by resonant inelastic light scattering, Nano Letters 6 (3), 478-482 (2006). (10.1021/nl0524492)

18.  T. Rosenblum-Dadosh, Y. Gordin, R. Krahne, I. Khivrich, D. Mahalu, V. Frydman, J. Sperling, A. Yacoby and I. Bar-Joseph, Measurement of the conductance of single conjugated molecules., Nature 436, 677 (2005). (http://www.nature.com/nature/journal/v436/n7051/full/nature03898.html)

19.  D. Tarì, M. De Giorgi, F. Della Sala, L. Carbone, R. Krahne, L. Manna, R. Cingolani, S. Kudera and W. J. Parak, Optical properties of tetrapod-shaped CdTe nanocrystals, Applied Physics Letters 87, 224101 (2005) (10.1063/1.2130727)

20.  M. De Giorgi, D. Tari, L. Manna, R. Krahne and R. Cingolani,, Optical properties of colloidal nanocrystal spheres and tetrapods, Microelectronics Journal, 36 (3-6), 552-554 (2005) (10.1016/j.mejo.2005.02.074)

21.  L. Manna, M. de Giorgi, D. Tari’, L. Carbone, R. Krahne, M. Anni,  R. Cingolani, S. Kudera and W. Parak, Perspectives of Colloidal Nanocrystals in Nanoscience and Nanotechnology. Proceedings of the International School of Physics Enrico Fermi, “From Nanostructures to Nanosensing Applications” (2004)

22.  A. Della Torre, P. Visconti, G. Maruccio, R. Krahne, R. Rinaldi, and R. Cingolani, Fabrication of nanoelectrodes for hybrid molecular-electronic device. Proceedings of the 4th IEEE Conference on Nanotechnology, 456-458 (2004), (Munich, Germany - 17-09/08/2004).

23.  R. Krahne, T. Dadosh, Y. Gordin, A. Yacoby, H. Shtrikman, D. Mahalu, J. Sperling, and I. Bar-Joseph, Nanoparticles and Nanogaps: Controlled Positioning and Fabrication. Physica E 17: 498-502 (2003) (10.1016/S1386-9477(02)00848-2)

24.  R. Krahne, T. Dadosh, A. Yacoby, H. Shtrikman, J. Sperling, and I. Bar-Joseph, Fabrication of Nanoscale Gaps in Integrated Circuits. Applied Physics Letters 81, 730 (2002). (10.1063/1.1495080)

25.  D. Heitmann, V. Gudmundsson, M. Hochgrafe, R. Krahne, D. Pfannkuche, Far-infrared spectroscopy of tailored quantum wires, quantum dots and antidot arrays.Physica E 14 (1-2), pp 37-44 (2002). (10.1016/S1386-9477(02)00357-0)

26.  R. Krahne, V. Gudmundsson, Ch. Heyn and D. Heitmann. Inter-Dot Interaction in an Array of Elliptical Quantum Dots. Physica E 12 (1-4), pp. 892-895 (2002). (10.1016/S1386-9477(01)00455-6)

27.  V. Gudmundsson, A. Manolescu, R. Krahne, D. Heitmann, From single dots to interacting arrays. “Nano-Physics and Bio-Electronics", edited by T. Chakraborty, F. Peeters, and U. Sivan, published by Elsevier (2002).( http://arxiv.org/abs/cond-mat/0110323)

28.  R. Krahne, V. Gudmundsson, Ch. Heyn and D. Heitmann. Far-infrared excitations below the Kohn mode:Internal motion in a quantum dot. Physical Review B 63, 195303, (2001). (10.1103/PhysRevB.63.195303)

29.  R. Krahne, M. Hochgräfe, Ch. Heyn, D. Heitmann, M. Hauser and K. Eberl. Excitation of two-dimensional plasmons with cross-grating couplers. Physical Review B 62, 15345, (2000). (10.1103/PhysRevB.62.15345)

30.  R. Krahne, M. Hochgräfe, Ch. Heyn, and D. Heitmann. Bernstein modes in density modulated two-dimensional electron systems and quantum dots. Physical Review B 61, R16319, (2000). (10.1103/PhysRevB.61.R16319)

31.  M. Hochgräfe, R. Krahne, Ch. Heyn, and D. Heitmann. Pillow shape motion in antidot arrays. Physica E 6 (1-4): 507-509 (2000). (10.1016/S1386-9477(99)00095-8)

32.  M. Hochgräfe, R. Krahne, Ch. Heyn, and D. Heitmann. Anticrossing of the one-dimensional plasmon and the Kohn’s mode in periodically modulated quantum wires. Physical Review B 60, R13974, (1999). (10.1103/PhysRevB.60.R13974)

33.  M. Hochgräfe, R. Krahne, Ch. Heyn, and D. Heitmann. Anticyclotron motion in antidot arrays.             Physical Review B 60, 10680, (1999). (10.1103/PhysRevB.60.10680)

34.  C. Schüller, R. Krahne, G. Biese, C. Steinebach, E. Ulrichs, D. Heitmann, and K. Eberl. Multiple cyclotron resonances in GaAs-AlGaAs quantum wells detected by resonant inelastic light scattering. Physical Review B 56, 1037, (1997). (10.1103/PhysRevB.56.1037)

35.  C. Steinebach, R. Krahne, G. Biese, C. Schüller, D. Heitmann, and K. Eberl. Internal electron-electron interactions in one dimensional systems detected by Raman spectroscopy. Physical Review B 54, R14281, (1996). (10.1103/PhysRevB.54.R14281)

- Roman Krahne is consulting as experienced researcher in a “Transfer of Knowledge” program (NANOTAIL) the design of transport experiments on single nanodevices at the FORTH institute in Greece.

- Leader of peer-reviewed user projects at the Weizmann Institute of Science, Israel, and at the Molecular Foundry, Lawrence Berkeley Laboratories, USA, that aimed at novel approaches to contact and position single nanoparticles.