Preface: phys. stat. sol. (c) 6/1
Authors: Itoh Tadashi , Tanaka Koichiro , Schreiber Michael 
Published: December 2008

This issue is a collection of papers presented at the 8th International Conference on Excitonic Processes in Condensed Matter (EXCON'08) which was held in Kyoto, Japan on 22–27 June 2008.

The EXCON series of conferences organized in even‐numbered years since 1994 is dedicated to the inter‐disciplinary field of exciton physics, providing a forum for research communication among solid state physicists, photo‐chemists, photo‐biologists and materials scientists. In EXCON'08 the following exciton research topics were representatively depicted: quantum confined excitons and low dimensional systems, excitons in nanostructures and metamaterials, single‐exciton studies, micro‐spectroscopy of excitons, photo‐biological processes, Frenkel excitons in molecular aggregates, energy transfer, exciton–lattice interaction, photo‐induced phase transitions, ab initio calculations and computational simulations of exciton phenomena, exciton condensation and superfluidity, exciton coherence phenomena, quantum entanglement, cavity polaritons and their application, biexciton and multi‐exciton complexes, nonlinear optical phenomena, ultrafast studies of exciton phenomena, THz spectroscopy of excited states, spin dynamics, photonic crystals and their novel phenomena, inorganic and organic light emitters, laser materials, etc.

To promote communication between scientists working in different fields and different countries, the conference venue generally has rotated among Australia, Europe, America and Japan. The past conferences were held in Darwin (Australia, 1994), Kurort Gohrisch (Germany, 1996), Boston (USA, 1998), Osaka (Japan, 2000), Darwin again in 2002, Cracow (Poland, 2004) and Winston‐Salem (USA, 2006). The 2008 conference met on the campus of Kyoto University in the old capital of Japan.

The recently renovated clock tower of Kyoto University which is depicted in the conference logo was an adequate venue for the conference. For more than 80 years it has served as a beloved symbol of Kyoto University, which in Japan is the second‐oldest university founded 111 years ago.

The EXCON'08 conference was attended by 191 participants from 20 countries; 51 participants came from the outside of Japan. We had a delegation of 7 people from the US. Also Europe was underrepresented with 32 attendees, with 6 each from Germany and France and followed by the Netherlands with 4 participants. Larger than at the previous EXCON conference was the Chinese attendance of 5 scientists. Fortunately, 45 graduate students took advantage of the possibility to participate in an international conference. Those students coming from abroad took the privilege of getting partial financial support from the conference.

The total number of presentations was 167. 40 plenary lectures were given (20 of them invited and further 20 upgraded from the contributed oral presentations). 54 talks in “oral posters” and 73 posters were presented. The novel category of “oral posters” which was initiated at EXCON'06 in Winston‐Salem, USA, took a form which entails two oral presentations per paper, to be given in different sessions, as an innovative design of a repeat performance which widely eliminates the conflict of interests in the audience of parallel sessions. In Kyoto, each speaker had twice the chance for presentation, in the morning (15 min) and in the afternoon (15 min) on 24 June. Informality is the mark of these sessions, so the speaker may present a talk and then take questions up to the time limit just like a typical oral session, or he/she may take the entire time for presentation and then adjourn with interested listeners for extended discussion at refreshments or a whiteboard, or he/she may simply show the power point slides and answer questions for the full allotted time. It also depends on one's choice if one makes the same presentation in the afternoon as in the morning, or if one mainly explains results in the morning and discusses them in the afternoon. The “oral poster” format provides many benefits for clear and congenial scientific communication, more comfortable viewing of visual aids, and a good experience in oral presentations for students. The details of the first attempt of oral posters were explained in the preface of the EXCON'06 Proceedings (Phys. Status Solidi Proceedings of EXCON'06 (2006), p. VIII).

Traditional posters were presented by those who chose that option and by those who submitted two papers as oral posters, among which one was shifted to the traditional posters by the Program Committee. Even and odd numbers of presentations of the traditional posters were separated in time to avoid the situation that the poster presenters could not join the discussion for other posters. In the conference report that was published in Phys. Status Solidi B 245, 2533 (2008), a comprehensive overview of the main topics of the talks has already been given, which shall not be repeated here. As far as the contents are concerned, the wide scope of the conference guaranteed that each participant could find something new and exciting for him. The readers are invited to a general view on the full program on the webpage www.excon08.scphys.kyoto‐u.ac.jp.

It should be noted that Professor William M. Yen of the University of Georgia, Athens, USA, who was one of the important members of the International Advisory Committee of EXCON'08, one of the past chairmen and a steadfast supporter of the EXCON conferences from the beginning, passed away in January 2008 during the preparation process of EXCON'08. The conference started with a short but solemn session dedicated to the memory of Professor Yen where commemorative addresses recalled how instrumental Bill Yen had been in getting the conference series running in the beginning. In order to know the details including his scientific contribution to a variety of fields, one is requested to read the memorial article following this preface.

The deadline for the submission of manuscripts for these proceedings was automatically enforced by the web‐submission page. It had been set to one week in advance of the conference so that contributors, guest editors and especially referees could attend the main part of refereeing before the meeting. We were able to send nearly two thirds of the 106 submitted manuscripts to referees before the beginning of the conference, the remaining manuscripts were assigned to referees during the first two days of the conference. Until the end of the meeting more than three fourths of the papers had been refereed and returned to the authors, and one third of those had already been accepted, most of them in revised form. It is a pleasure for us to thank in particular Akira Ishikawa and Hisaki Oka for their untiring support in the editorial office, as well as Cornelia Schreiber for performing the tedious work of the layout editing. Two weeks after the conference three fifths of the papers were accepted for the conference proceedings. The possibility to publish particularly interesting, topical, important, or outstanding results in the regular journal Phys. Status Solidi B required review by a second referee. This option had been chosen by 42 authors. However, in exactly half of these cases the first referee already denied that the manuscript was appropriate for such an upgrade. Following the experience from the previous conference we started the second round of refereeing only in the middle of July, when the first referees had agreed to such an upgrade. We are grateful that this second round also proceeded very fast, so that about four fifths of all manuscripts could be forwarded to the publisher in final form until the end of July, and 19 further manuscripts in the following three weeks. With pleasure we take this opportunity to thank also the publisher for the fast treatment of all manuscripts.

The Guest Editors would like to express their gratitude to the Institute for Integrated Cell‐Material Sciences (iCeMS) of Kyoto University, co‐organizer of EXCON'08, for its support of publishing the proceedings, and are also grateful to the support of the following organizations: Commemorative Organization for the Japan World Exposition ('70), Inoue Foundation for Science, Japan Science and Technology Agency, Japan Society for the Promotion of Science, Kansai Research Foundation for Technology Promotion, Kyoto Convention Bureau, and the Murata Science Foundation.

The traditional emphasis of EXCON conferences on promoting the contributions of young researchers was embodied in the competition for the EXCON Prizes. Owing to the sponsors' generosity, this time the harvest of prizes was particularly rich. Like for the previous EXCON'06 conference, the publisher Wiley‐VCH funded again two equivalent Phys. Status Solidi Young Researcher Awards for outstanding oral contributions, each award consisting of a certificate, a monetary prize of 250 Euro, and a 150 Euro voucher for Wiley books. In addition, the Mitsubishi Electric Corporation established two prizes of 40000 Yen for the best posters presented at the conference. For all the prizes the age of at most 35 years was the eligibility limit; there was also the additional stipulation that the applicant did not hold a professorial position.

The task of the contest jury conducted by Prof. Piotr Petelenz, Chairman of the Prize Nomination Committee, was a difficult one: there were 20 posters competing for the Mitsubishi Prizes, and the total number of 26 contributions competing for the Wiley Awards. This latter category covered mostly oral posters, but encompassed also those which had been up‐graded by the Organizing Committee to become plenary lectures with invited‐talk status. By and large, the standard of all contest entries was very high and selection was difficult. It was based primarily on the originality of the competing contributions, with substantial credit for the quality of execution of the well‐conceived idea and some credit for the quality of presentation. The prizes were finally awarded to Ramunas Augulis (R. Augulis, M. Klok, B. L. Feringa, and P. H. M. van Loosdrecht, “Light‐driven rotary molecular motors: ultrafast optical study”, Phys. Status Solidi C 6, 181 (2009), this issue) and to Ryosuke Watanabe (R. Watanabe, M. Iwanaga, and T. Ishihara, “s‐polarization Brewster's angle of stratified metal–dielectric metamaterial in optical regime”, also part of the proceedings and published as Editor's Choice in Phys. Status Solidi B 245, 2696 (2008)). The outstanding feature of the former contribution consists in the inventive use of chiral interactions to guarantee that the constructed molecular motor can turn only in one direction, which enables it to work cyclically. At the stage of implementation the very fact that the system is provably operative is a major accomplishment. The latter paper is a culmination of a long series of attempts by various research groups to make a metamaterial with negative refractive index in the optical range. The materials considered so far and successfully constructed for the microwave region were periodic arrays of cleverly shaped objects (split rings) that emulate the function of resonating electrical circuits. Successful construction of a relatively simple layered structure that can do the same in the visible is a major success; the demonstration of the relevant property based on measurements of Brewster's angle for the s wave is a convincing proof of the authors' ingenuity and experimental prowess.

Also the posters represented a very high standard. The Mitsubishi Electric Prizes were finally awarded to Akihiro Ueda (A. Ueda, K. Matsuda, T. Tayagaki, and Y. Kanemitsu, “Mechanism of carrier multiplication in carbon nanotubes studied by ultrafast pump–probe spectroscopy”) and Takaaki Yoshioka (T. Yoshioka, K. Miyajima, M. Ashida, and T. Itoh, “Infrared transient absorption spectra for excited transition of excitons and biexcitons in CuCl”). In the former work carrier multiplication in single‐walled carbon nanotubes was observed for the first time, using femtosecond pump–probe spectroscopy. The latter contribution reported on the first observation of the infrared transition between the ground and excited states of a biexciton in CuCl analogous to the Lyman transitions for a single exciton.

The Guest Editors of this issue are pleased to congratulate all the prize winners, as well as those who applied for the competition.

The Guest Editors express their gratitude to all the authors and the referees, while the organizers of EXCON'08 would like to take the opportunity to thank the members of the International Advisory Committee and of the local staff (primarily Kyoto University staff and students), the invited speakers, the session chairmen and all the attendees for their contribution to the conference.

At www.excon08.scphys.kyoto‐u.ac.jp additional information and photographs of the conference activities can be found.

It is a pleasure to announce that the next conference of the EXCON series will be held in 2010 in Australia and will be once more chaired by Prof. Jai Singh, the organizer of EXCON'94 and EXCON'02. We believe that we express the attitude of most or even all participants when we state that we are looking very much forward to the meeting.

September 2008

Osaka, Kyoto and Chemnitz