Bratos, Savo

Savo Bratoz se je rodil 1926 v Trstu. Študiral je fiziko in diplomiral 1951 na univerzi v Ljubljani. S temo o karakterističnih nihajnih frekvencah molekul je 1955 doktoriral na ljubljanski univerzi pod vodstvom prof. D. Hadžija. Svoj drugi doktorat o infrardečih spektrih komprimiranih plinov pod vodstvom prof. R. Daudela je zagovarjal 1964 na univerzi v Parizu. 1956 je bil imenovan na mesto »Attaché de Recherche« v Centre National de la Recherche Scientifique v Franciji. Pozneje je tam tudi dosegel mesti »Chargé« in »Maître de Recherche«. 1969 je bil izvoljen za docenta in 1973 za rednega profesorja univerze Pierre et Marie Curie v Parizu. Še danes deluje tam kot zaslužni profesor. 1983 mu je European Physical Society zaupala organizacijo Sekcije za tekočine v okviru Divizije za kodenzirano materijo. Tej sekciji je predsedoval med 1983 in 1991. Slovenska akademija znanosti in umetnosti ga je počastila z izvolitvijo za dopisnega clana (1987). Postal je tudi redni član Evropske akademije znanosti, umetnosti in literature (1995). Istega leta ga je odlikovala univerza Pierre et Marie Curie. 1992 ga je Centre National de la Recherche Scientifique imenoval za direktorja Projekta za ultrahitro kemično kinetiko za obdobje osmih let. Poleg tega sta ga poljska Akademija znanosti in umetnosti v Krakovu (1999) in poljska Akademija znanosti v Varsavi (2000) izvolili za dopisnega člana. Univerza v Wroclawu mu je podelila leta 2006 naslov častnega doktorja.
Glavno področje znanstvenega dela S. Bratoza je molekulska dinamika tekočin. V tem okviru je raziskoval mnoge probleme infrardeče in Ramanske spektroskopije. Zadnjih petnajst let pa je tudi uporabljal moderne tehnike časovno ločene optične spektroskopije in časovno ločenega uklona žarkov X. Med najpomembnejše znanstvene prispevke prof. S. Bratoza štejemo naslednja dela: Z D. Hadžijem sta ponudila razlago pojavov, ki jih vodikova vez vnaša v infrardeče spektre tekočin. Poudarila sta vlogo anharmoničnosti na tem področju (1). Njuna teorija je prodirala le počasi, več kod deset let je bilo potrebnih, da je bila sprejeta. Bratoz je tudi izdelal statistično teorijo spektralnih profilov v infrardečih in Ramanskih spektrih enostavnih tekočin (2,3). Predložil je eksperimentalno metodo, ki dopušča ločeno obravnavo nihajne in rotacijske relaksacije v teh sistemih. Ta metoda, imenovana VV-VH, je danes v splošni uporabi v spektroskopiji. Njegovi novejši prispevki pa uporabljajo ultrahitre tehnike. Tako je S. Bratoz preučeval gibanja kisikovih atomov v vodikovi vezi OH…O v vodi s pomočjo časovno-ločene infrardeče spektroskopije. To delo, ki sta ga objavila S. Bratoz in G. Gale 1999, je omogočilo prvo »filmanje« gibanja vodikove vezi v realnem času na skali femtosekunde. Drugi prispevek te vrste je delo S. Bratoza in M. Wulffa, ki sta raziskovala kemično dinamiko v tekočinah s pomočjo ultrahitrih pulsov žarkov X velikega sinhrotrona v Grenoblu (5). Njuna študija obravnava ponovno tvorbo molekul joda, ki so jih laserski pulsi predhodno razdrobili. Atomskemu gibanju sta sledila vse do dotika obeh atomov. Sto let po Roentgenu, Braggu in Laueju je tako postalo mogoče »filmati« rojstvo nove molekule.
Glavni prispevki :
(1) Infrared spectra of molecules with hydrogen bonds, J. Chem. Phys. 63 (1957), 991 (with D. Hadzi).
(2) Infrared study of liquids. (I) Theory of infrared spectra of diatomic molecules in inert solutions, J. Chem. Phys. 52 (1970), 439 (with J. Rios and Y. Guissani).
(3) Raman study of liquids. I. Theory of Raman spectra of diatomic molecules in inert solutions, Phys. Rev. A4 (1971), 1078 (with E. Maréchal).
(4) Femto second dynamics of hydrogen bonds in liquid water: a real time study, Phys. Rev. Lett. 82 (1999), 1068 (with G.M. Gale, G. Gallot, F. Hache, N. Lascoux and J-Cl. Leicknam).
(5) Visualizing chemical reactions in solution by pico second x-ray diffraction, Phys. Rev. Lett. (92 (2004), 125505 (with A. Plech, M. Wulff, F. Mirloup, R.Vuilleumier, F. Schotte and Ph. A. Anfinrud).

(junij 2011)

Savo Bratoz was born in 1926 in Trieste, Italy. He graduated in 1951 in physics at the University of Ljubljana, Slovenia. He prepared two Ph D’s, a first in 1955 on characteristic vibrational frequencies, under supervision of Prof. D. Hadzi of the University of Ljubljana, and a second in 1964 on infrared spectra of compressed gases, under supervision of Prof. R. Daudel of the University of Paris. In 1956, he was appointed Attaché de Recherche in the Centre National de la Recherche Scientifique. Later on, he was successively Chargé and Maître de Recherche in the same scientific institution. In 1969 he was nominated Associated and, in 1973, Full Professor of Physics at the University Pierre et Marie Curie in Paris. Actually, he is Professor Emeritus of the same University. The European Physical Society charged him, in 1983, to create a Liquids Section in the frame of its Condensed Matter Division. He chaired it from 1983 to 1991. In 1987, he was elected corresponding member of Slovenian Academy of Science and Arts, and in 1995 full member of the European Academy of Arts, Sciences and Humanities. The same year, the University Pierre et Marie Curie honoured him with a medal of this University. In 1992, the Centre National de la Recherche Scientifique nominated him Director of a Research Project on ultra fast chemical processes in liquids for a period of eight years. Moreover, in 1999 Polish Academy of Sciences and Arts in Krakow, and in 2000 Polish Academy of Sciences in Warsaw elected him foreign member of these institutions. Finally, University of Wroclaw attributed him the title of Doctor Honoris Causa in 2006.
The scientific activity of S. Bratoz mainly concerns the study of molecular dynamics of liquids. Many problems of infrared and Raman spectroscopy, as well as of incoherent neutron spectroscopy were studied in this frame. He also employed ultrafast techniques such as time-resolved optical spectroscopy or time-resolved x-ray diffraction. The most important contributions are as follows. He first succeeded, with D. Hadzi, to explain infrared characteristics of H-bonded system in terms of anharmonicity of vibrations affected by this intermolecular force (1). The acceptation of this proposal was slow, and required more than ten years of discussions and controversies. He next elaborated a statistical theory of infrared and Raman band shapes of Van der Waals liquids (2, 3). He proposed an experimental method to disentangle spectral effects of vibrational and rotational relaxation in liquids. Termed the VV – VH separation method, this procedure is actually of current use in spectroscopic laboratories. From the other side, S. Bratos and G. Gale tracked oxygen motions of an OH...O bond in water by time-resolved infrared spectroscopy (4). For the first time they succeeded to “film” these motions on femtosecond time scales. Finally, in collaboration with M. Wulff, he explored atomic motions by time-resolved x-ray diffraction (5). In their experiment, the recombination of laser dissociated iodine atoms in solution was monitored by synchrotron generated x-ray pulses. This tracking was followed up to the final moment when the two recombining atoms touch each other. Hundred years after Roentgen, Bragg and Laue, “filming” the birth of a new molecule by x-rays became possible. The references of a few major papers are as follows:
(1) Infrared spectra of molecules with hydrogen bonds, J. Chem. Phys. 63 (1957), 991 (with D. Hadzi).
(2) Infrared study of liquids. (I) Theory of infrared spectra of diatomic molecules in inert solutions, J. Chem. Phys. 52 (1970), 439 (with J. Rios and Y. Guissani).
(3) Raman study of liquids. I. Theory of Raman spectra of diatomic molecules in inert solutions, Phys. Rev. A4 (1971), 1078 (with E. Maréchal).
(4) Femto second dynamics of hydrogen bonds in liquid water: a real time study, Phys. Rev. Lett. 82 (1999), 1068 (with G.M. Gale, G. Gallot, F. Hache, N. Lascoux and J-Cl. Leicknam ).
(5) Visualizing chemical reactions in solution by pico second x-ray diffraction, Phys. Rev. Lett. (92 (2004), 125505 (with A. Plech, M. Wulff, F. Mirloup, R.Vuilleumier, F. Schotte and Ph. A. Anfinrud).

(August 2010)