Photoelectric photometry of Comet Halley from Mt Tamborine observatory

in Vistas in Astronomy (1988), 31

Post-perihelion photoelectric observations of comet Halley carried out during several weeks are reported. The measurements confirm the existence of large-amplitude night-to-night changes.

Photoelectric scans of comet Halley.

in Diversity and Similarity of Comets (1987, September 01)

The authors compare radial photometric scans of comet Halley obtained in April 1986 at the European Southern Observatory, La Silla, Chile, with theoretical profiles derived from Haser's model.

Photoelectron Spectroscopy of Vinyl Bromide and Intramolecular Dynamics of the ionic B state.

in Chemical Physics (2000), 256

In this paper we report the He(I) photoelectron spectrum (PES) and the threshold photoelectron spectrum (TPES) of C2H3Br. The fine structure in the first two ionic states in the He(I) spectrum is assigned ... [more ▼]

In this paper we report the He(I) photoelectron spectrum (PES) and the threshold photoelectron spectrum (TPES) of C2H3Br. The fine structure in the first two ionic states in the He(I) spectrum is assigned to progressions belonging partially to previously unobserved vibrational modes. The TPES has been measured between 9.0 and 25.0 eV, and the photon energy range of 9.8-12.0 eV has been investigated in more detail. Extensive calculations with the GAUSSIAN set of programs have been performed to help in the assignment of the observed features. Furthermore, a conical intersection between the A2A" and the B2A" states was found to take place along the C-Br stretching coordinate. Intramolecular dynamics of the B2A" state, initially prepared in the Franck-Condon region, was probed by the Fourier transform of the spectrum. The B2A" state is almost readily depleted, most probably due to a very effective internal cnversion through the conical intersection. [less ▲]

Photogrammetry for forest inventory

Conference (2013, March 12)

La photographie à l’épreuve de la chair : mises en jeu et mises en scène du corps dans la photographie contemporaine

in Bawin, Julie (Ed.) Art actuel et Photographie (2008)

La photographie aérienne en période de sècheresse comme source de renseignements géologiques en Wallonie

in Bulletin de la Société Géographique de Liège (2001), 40(2001-1), 33-40

La photographie diagnostic de la contemporanéité

in Association Française de Sémiotique (2007)

immigration, Cet article porte sur l’efficacité politique d’une série photographique qui problématise des questions socioculturelles contemporaines telles l’immigration, l’exploitation et l’éthique du ... [more ▼]

immigration, Cet article porte sur l’efficacité politique d’une série photographique qui problématise des questions socioculturelles contemporaines telles l’immigration, l’exploitation et l’éthique du travail. L’image photographique devient une ressource dans les mains des acteurs sociaux et fait fonction de diagnostic des tensions du contemporain. La photographie permet de « reconnaître à travers » (c’est-à-dire « diagnostiquer ») et de formuler des jugements. Le potentiel sémantique du diagnostic engendré par cette série et la force illocutoire des jugements qui y sont inscrits fonctionnent comme une sorte d’« argumentation par images ». L’analyse de cette série photographique, réalisée par le photographe et théoricien Allan Sekula, nous a amené à nous interroger sur la relation entre image, corpus, genres d’afférence et statuts (documentaire et artistique). [less ▲]

Photography as a Witness of Theatre

in Recherches Sémiotiques/Semiotic Inquiry (2008), 27-28(1-2), 43-57

My paper investigates the meeting of theatre and photography in ‘theatre photography’. Recognizing that both art forms can determine theoretical and philosophical views on representation and self ... [more ▼]

My paper investigates the meeting of theatre and photography in ‘theatre photography’. Recognizing that both art forms can determine theoretical and philosophical views on representation and self-representation, I aim to compare their visual strategies and the way they construct point of view. In the process several questions are raised: do qualities of photographs belong to objects photographed or to photographs themselves? How important is the object that ‘triggers’ the view? Should the theatre photographer place his camera anywhere? What of framing? In the second section I offer an analysis of photographs taken by Roger Pic in 1957 during the Paris performance of Brecht’s Mother Courage and Her Children by the Berliner Ensemble. This analysis seeks to demonstrate that theatre photography, which often seen as an example of documentary photography, can reach artistic status, provided it relies on enunciative strategies that express what cannot otherwise be photographed in a ‘direct’ manner, namely the characters’ words and emotions. [less ▲]

Photoinduced birefringence and diffraction efficiency in azo dye doped or grafted polymers: theory versus experiment of the temperature influence

in Journal of the Optical Society of America. B, Optical Physics (2000), 17(5), 729-740

We have investigated the influence of the temperature on the photoinduced birefringence as well as on the diffraction efficiency of azo dye doped or grafted polymers. The samples are composed of three ... [more ▼]

We have investigated the influence of the temperature on the photoinduced birefringence as well as on the diffraction efficiency of azo dye doped or grafted polymers. The samples are composed of three polymer matrices containing 2, 5-dimethyl-4-(p-nitrophenylazo anisole). We propose two theoretical models to explain the experimental increase of both phenomena when the temperature is decreased. Models are based on the statistical angular distribution of the chromophores that depends on the intensity of the polarized laser beam in the media, counteracted by the thermal agitation. Parameters introduced in both models can be used to characterize the polymeric system properties. [less ▲]

The Photoionization Dynamics of Methyl Iodide (CH3I): a joint Photoelectron and Mass Spectrometric Investigation.

in Journal of Physics : B Atomic Molecular & Optical Physics (2010), 43(10), 105101

The threshold photoelectron (TPES) and the photoionization mass spectrometric (PIMS) study of CH3I in the 8-20 eV photon energy range are presented. The interpretation and assignments are supported by ab ... [more ▼]

The threshold photoelectron (TPES) and the photoionization mass spectrometric (PIMS) study of CH3I in the 8-20 eV photon energy range are presented. The interpretation and assignments are supported by ab initio calculations. The TPES shows many new discrete features in the Jahn-Teller split ground X 2E (2A'-2A”) state of CH3I+. A new continuous band starting at about 11.7 eV is detected. These observations are essentially correlated with autoionizing transitions. This interpretation is supported by constant ion state (CIS) spectroscopy. A large enhancement of the transitions to the A 2A and B 2E ionic states is ascribed to large autoionizing contributions. Based on the present calculations, the weak to very weak bands in the 18.0 eV-23.0 eV photon energy range are mainly assigned to 2a1-1 ionization and to double excitations corresponding essentially to the 2e-2 4a11 and 3a1- 1 2e-1 4a11 configurations. The photoionization mass spectrometric study allowed us to investigate in detail the ionization and dissociation of CH3I+ leading to CH2+, CH3+, I+ and CH2I+ from the threshold up to 20 eV photon energy. The experimental data are compared to ab initio calculated dissociation energies. The threshold of appearance of CH3+, I+ and CH2I+ fragments are concentrated in the 12.2-12.7 eV photon energy range. All three exit channels are correlated with the ground state of CH3I+ via nonadiabatic transitions. All three fragment ions have to appear through predissociation of the ionic X 2E state and autoionizing dissociation from the (2E3/2)6p Rydberg state. This interpretation is strongly supported by the photoabsorption spectrum measured recently in the same photon energy range [1]. At higher energies, beside direct or predissociation of the A 2A1 and B 2E states of CH3I+, autoionization is also suggested to contribute to the fragmentation in all decay channels. [less ▲]