Lab. OPTICS AND SPECTROSCOPY

Optics and Spectroscopy of Thermotropic Liquid Crystals

In the last 10 years, the group has been working on electro-optical and structural properties of smectic and nematic thermothropic liquid crystals. Its most significant contributions during that period are:

- The finding of the unique structural phase transition in the nematic liquid-crystal phase of smectic C-order;

- The finding of the chiral smectic (_C_G) phase of lowest symmetry (triclinik) in nanocomposites of thermotropis liquid crystals built of dimer molecules and carbon nanotubes.

- A successfully defended PhD thesis and a position for a new PhD student.

Boiko Katranchev received the Young scientist award “Acad. Ivan Geshov” of BAS in physics.

A monograph by M. Petrov has been published: „Optical and electro-optical properties of liquid crystals: nematic and smectic phases”.

Boyko Pavlov Katranchev

Academic background:

May 2008

February 2008

November 2007

2002-2007

2001

1995

Assist. Prof. in Department of Optics and Spectroscopy, Institute of Solid State Physics

Ph.D. in physics

Defense of Ph.D. thesis

Title of Ph.D. thesis: ‘Surface and electrooptical properties of the nematic liquid crystals with short range smectic C order’

Ph.D. student, Institute of Solid State Physics

Bulgarian Academy of Sciences

MS degree in Laser Physics and Solid State Physics, Departments of Sofia University

Title of M.S. thesis: ‘Temperature photoacoustic module’

Sofia Mathematical High School

Professional and Scientific Awards:

Award of Bulgarian Academy of Sciences for the youngest scientists ‘Acad. Ivan Evstratiev Geshov’ in Physics for 2006.

Member of: Bulgarian Physics Society; Bulgarian Liquid Crystals Society.

Research interests: Liquid crystals, Smectic C, Dendrites, Electroconvection, Surface memory effect, Nanocomposites, Carbone nanotubes.

Publications

1. B.Katranchev, H. Naradikian, E. Keskinova, M.P. Petrov and J.P.Marcerou, ‘The elekcroconvective dendrites in nematics with short range smectic order liquid crystal – 4,n-alkyloxybezoic acids’, Liq. Cryst. (UK), 31, No. 12, 1663–1676 (2004).

2. Antonova K., Katranchev B., Petrov M., Marcerou J.P., Baran J., Ratajczak H, ‘FT-Far IR spectroscopy and microtextural polarization analysis of complexes: nematics with hydrogen bonded in dimers molecules and hydroxypiridine’, J. Mol. Structure, 694, 105–113 (2004).

3. H.Naradikian, B. Katranchev, E.Keskinova and M. Petrov, Chirality in hydrogen bonded in dimers achiral liquid crystals, Nanoscience & Nanotechnology, Heron Press 4, 219–222, (2004).

4. B.Katranchev and M.Petrov, ‘Surface memorization driven by surface polar angle values in achiral and induced by mixture chiral liquid crystals’, Bul. J. Phys., 31, 111-117 (2004).

5. H. Naradikian, B.Katranchev, E. Keskinova, J.P.Marcerou and M.P. Petrov, ‘Thermal and elecroconvective dendrites in the nematic phase with short range smectic order of 4,n-heptyl and 4,n-octyloxybenzoic acids’, Bul. J. Phys., 31, 118-129 (2004).

6. H. Naradikian, B.Katranchev, T.Angelov, R.Ugrinov, ‘Optical properties in polymer stabilized liquid crystal indicator used in the thermometry’, Bul. J. Phys., 31, 130-134 (2004).

7. B. Katranchev and M. Petrov, ‘Surface orientation of smectics C and nematic with short range smectic C order using holographic diffraction grating’, Journal of Optoelectronics and Advanced Materials, 7, p. 265-268, (2005).

8. B. Katranchev, H. Naradikian and M. Petrov, ‘The role of hydrogen bonding for initiation of chirality, dendrites and physical gel in nematic with short range smectic C order’, Journal of Optoelectronics and Advanced Materials, 7, p. 273-276, (2005).

9. T. Angelov, B. Katranchev and M. Petrov, ‘High temperature formation of polymer – dispersed hydrogen bonded liquid crystals’, Journal of Optoelectronics and Advanced Materials, 7, p. 281-284, (2005).

10. Kr. Panayotov, T. Angelov, H. Naradikian, B Katranchev and M. Petrov ‘The optical fibers obtained by liquid crystal photonic bandgap, Photonic Crystal Fibers (PCFs)’, Nanoscience & Nanotechnology, Heron Press, 6, 100-103, 2006.

11. Б. П. Катранчев, ‘Повърхнинна памет управлявана чрез повърхнинните полярни ъгли в ориентирани смектични С течни кристали’, ‘Списание на БАН’ (кн. 1/2006) p. 53.

12. M. Petrov, B. Katranchev, E. Keskinova and H. Naradikian, ‘The electroconvection in dimeric nematic liquid crystals’, Journal of Optoelectronics and Advanced Materials, 9, 438-441, 2007.

13. M. Petrov, B. Katranchev and H. Naradikian, ‘Surface anchoring breaking in smectic C liquid crystals’, Journal of Optoelectronics and Advanced Materials, 9, 442-445, 2007.

14. M. Petrov, B. Katranchev, H. Naradikian, T. Angelov, K. Panajotov and A. Zheltikov, ‘Electrically tunable chiral nematic liquid crystal photonic crystal fibers’, Journal of Optoelectronics and Advanced Materials, 9, 446-448, 2007.

15. Petrov, M., Keskinova, E., Katranchev, B., ‘The electroconvection in the nematic liquid crystals with short range smectic C order’ Journal of Molecular Liquids, 138, 130-138, 2008.

16. B. Katranchev, M. Petrov, ‘Prewavy electrohydrodynamic instability in dimeric nematic liquid crystals with short range smectic C order’, Compt. rend. Acad. bulg. Sci., 62, No 3, 329-334, 2009.

17. M. P. Petrov, and B. Katranchev, ‘The bulk twist action on the single local monocrystals of the smectic C liquid crystal’, Phase Transitions, 82 (5), 366 – 376, 2009.

18. M. Petrov, E. Keskinova, H. Naradikian and B. Katranchev, ‘Diffraction grating effect in smectic C and nematic liquid crystals at obliquely incident coherent laser light’, Journal of Optoelectronics and Advanced Materials, 11 (9), 1226 - 1229, 2009.

19. B.Katranchev, H. Naradikian, E. Keskinova and M. Petrov, ‘The role of the negative electroconductivity anisotropy at the electroconvection in nematic liquid crystals with short range smectic C order’, J. Phys.: Conf. Ser., 253, 012062, 2010.

20. M. Petrov, E. Keskinova, B. Katranchev and H. Naradikian, ‘Electroconvection in dimeric nematic liquid crystals with short range smectic C order. Dynamical characteristics’, Liquid Crystals, 38 (1), 41-52, 2011.

21. M Petrov, B Katranchev, P M Rafailov, H Naradikian, U Dettlaff-Weglikowska and E Keskinova, ‘Optical properties of dimeric liquid crystals doped with single-walled carbon nanotubes’, J. Phys.: Conf. Ser., 398, 012035, 2012.

22. B. Katranchev, M. Petrov, I. Bineva, Z. Levi, M. Mineva, ‘Smectic C liquid crystal growth through surface orientation by Zn_xCd_1-xSe thin films’, J. Phys.: Conf. Ser., 398, 012036, 2012.

23. M. Petrov, B. Katranchev, P.M. Rafailov, H. Naradikian, U. Dettlaff-Weglikowska and E. Keskinova, ‘Smectic C liquid crystal growth and memory effect through surface orientation by carbon nanotubes’, J. Mol. Liq., 180, 215–220, 2013.

24. M. Petrov, B. Katranchev, P.M. Rafailov, H. Naradikian, U. Dettlaff-Weglikowska, E. Keskinova and T. Spassov, ‘Phases and properties of nanocomposites of hydrogen-bonded liquid crystals and carbon nanotubes’, Phys. Rev. E, 88, 042503, 2013.

25. B. Katranchev, M. Petrov, I. Bineva, Z. Aneva, and D. Nesheva, ‘Orientation of dimeric liquid crystals through Zn_XCd_1-_XSe nanostructured surfaces’, Nanoscience & Nanotechnology, 13, 98-100, 2013.

26. B Katranchev, M Petrov, E Keskinova, H Naradikian, P M Rafailov, U Dettlaff-Weglikowska and T. Spassov, ‘Liquid crystal nanocomposites produced by mixures of hydrogen bonded achiral liquid crystals and functionalized carbon nanotubes’, J. Phys.: Conf. Ser., 558, 012024, 2014.

27. K. Zhelyazkova, G. Dyankov, M. Petrov, B. Katranchev, ‘Surface plasmon resonance on the surface: metal - liquid crystal layer’, J. Phys.: Conf. Ser., 558, 012023, 2014.

28. K Zhelyazkova, M Petrov, B Katranchev, G Dyankov, ‘An anisotropic stratified structure for surface plasmon excitation’, Proc. SPIE, 9447, 94470C, 2015.

29. B. Katranchev, M Petrov, ‘Phase transitions in nanocomposites of hydrogenbonded dimeric liquid crystals with mesogenic and non-mesogenic components, Phase transitions, 89 (2), 115-132, 2016.