M. H. Tailleur

Bio: M. H. Tailleur is an academic researcher from French Alternative Energies and Atomic Energy Commission. The author has an hindex of 1, co-authored 1 publications receiving 7 citations.

Etude des conditions d'initiation de la pentrite (PETN) par spectrométrie raman ultra‐rapide

Abstract: La diffusion Raman ultra-rapide permet d'etudier les phenomenes tres brefs qui president a la generation de la detonation dans des explosifs secondaires nitres. D'apres une etude theorique precedente, il existe pour ces explosifs une liaison de type RNO2 par ou debute la reaction de decomposition explosive sous choc. Cette etude theorique a ete verifiee experimentalement sur deux de ses conclusions: le changement de phase de la pentrite et les modifications de structure electronique affectant l'une des liaisons ONO2 sous choc. Pour ce faire, une etude de la pentrite a l'etat monocristallin a ete realisee par spectrometrie Raman classique en vue d'une attribution complete du spectre. Il a ete en meme temps observe des eclatements des modes polaires du fait de l'absence de centre d'inversion dans la maille. L'etude experimentale entreprise par la suite a necessite une mise au point du montage Raman avant de conduire aux resultats montrant, outre de faibles deplacements de frequence, d'importantes variations d'intensite de quelques raies pour une certaine pression de choc.

Shock physics at the nanoscale [Invited]

Abstract: Shock waves can achieve extreme states of pressure and temperature, of particular interest because those conditions can result in non-equilibrium material dynamics that evolve on ultrafast timescales. Examples of such phenomena include shock-induced chemistry and phase transitions. Traditional plate impact methods lack the necessary time and space resolution needed to observe the onset of ultrafast nanoscale phenomena. Sub-picosecond time scale and nanometer spatial scale shock compression and diagnostics methods have been developed to surmount such difficulties. This paper reviews a number of nanoscale shock wave generation methods, as well as the diagnostics that are applicable at these restrictive time and spatial scales.

Insight into the Chemistry of PETN Under Shock Compression Through Ultrafast Broadband Mid-Infrared Absorption Spectroscopy.

Abstract: Thin films of pentaerythritol tetranitrate (PETN) were shock compressed using the laser driven shock apparatus at Los Alamos National Laboratory (LANL). Two spectroscopic probes were available to this apparatus: visible white light transient absorption spectroscopy (VIS) from 400 to 700 nm and mid-infrared transient absorption spectroscopy (MIR) from 1150 to 3800 cm-1. Important PETN vibrational modes are the symmetric and antisymmetric NO2 stretches at 1280 and 1650 cm-1, respectively, as well as CH stretches at ∼2900 cm-1. Shock strength was varied from approximately 3 to 55 GPa to span from the chemically unreactive regime to the regime in which fast chemical reaction took place on the 250 ps time scale of the measurements. VIS and MIR results suggest irreversible chemistry was induced in PETN at pressures above 30 GPa. At lower shock pressures, the spectroscopy showed minimal changes attributable to pressure induced effects. Under the higher-pressure reactive conditions, the frequency region at the antisymmetric NO2 stretch mode had a significantly increased absorption while the region around the symmetric NO2 stretch did not. No observable increased absorption occurred in the higher frequency regions where CH-, NH-, and OH- bond absorptions would be observed. A broad absorption appeared on the shoulder at the red-edge of the CO2 vibrational band around 2200 cm-1. In addition to the experiments, reactive molecular dynamics were carried out under equivalent shock conditions to correlate the evolution of the infrared spectrum to molecular processes. The simulations show results consistent to experiments up to 30 GPa but suggest that NO and NO2 related features provided the strongest contributions to the shocked infrared changes. Proposed mechanisms for shocked PETN chemistry are analyzed as consistent or inconsistent with the data presented here. Our experimental data suggests C≡O or N2O bond formation, nitrite formation, and absence of significant hydroxyl or amine concentrations in the initial chemistry steps in PETN shocked above 30 GPa.

Single-pulse Raman scattering studies of heterogeneous explosive materials

Abstract: Raman scattering from ambient and shock-loaded heterogeneous (compressed pure polycrystalline) explosive materials has been examined using single-pulse laser excitation. In the case of triamino-trinitrobenzene (TATB), intense nonlinear scattering at 1170 cm−1 has been observed.

Shock wave diagnostics by time-resolved infrared radiometry and non-linear raman spectroscopy

Abstract: Two different kinds of experimental techniques have been used to probe shocked materials. Inverse Raman (Raman-induced loss) spectroscopy (IRS) was used for time-resolved shock wave experiments. Explosive loading of stainless steel driver plates was used to shock cyclohexane and single-crystal pentaerythritoltetranitrate (PETN). Five GPa shocks in PETN and cyclohexane result in only small band frequency shifts. In a separate series of experiments, time-resolved infrared emission from shocked explosives with impedance matching, infrared transmitting windows was measured. Five nanosecond response-time radiometers with InSb and HgCdTe detectors have provided further insight into shock-induced reactions in explosives. Radiance histories of pressed TATB with IR windows exhibited resolved shock heating and following reaction heating and dramatic differences between particle size distributions pressed to the same density. Detonation wave infrared radiance histories from explosives with infrared transmitting windows provide a new experimental technique for detonation reaction zone structure. Recent single-frame, 12 ns-exposure image intensifier pictures of shocked explosives with impedance-matching windows show visible hot spots, and the results support the conclusions of the infrared data.

Raman spectroscopies in shock-compressed materials

Abstract: Spontaneous Raman spectroscopy, stimulated Raman scattering and coherent anti-Stokes Raman scattering have been used to measure temperatures and changes in molecular vibrational frequencies for detonating and shocked materials. Inverse Raman and Raman induced Kerr effect spectroscopies have been suggested as diagnostic probes for determining and phenomenology of shock-induced chemical reactions. The practicality, advantages, and disadvantages of using Raman scattering techniques as diagnostic probes of microscopic phenomenology through and immediately behind the shock front of shock-compressed molecular systems are discussed.