The archaeology of the military orders: the material culture of holy war

This paper reviews the current state of research into the archaeology of the military orders. It contrasts the advances made by historians and archaeologists, with the latter continuing to focus on the particularism of individual sites, with an emphasis on architectural analyses. Historians have contributed new insights by adopting a supranational approach. This paper argues that archaeologists can build on this by adopting a more problem-oriented, comparative approach. Drawing on examples from frontier and heartland territories, archaeological approaches are subdivided into material investment, material identity and cultural landscapes, to place sites of the military orders within a long-term, multi-scalar contexts. This contributes to a broader social and economic understanding of the orders, who contributed significantly to urbanisation, rural development and trade, and invested in material expressions of their authority and ideology. The paper concludes that more holistic, inter-regional approaches will move the archaeological study of the military orders forward

Ab initio investigation of the line-shape parameters for atmosphere-relevant molecular systems

International audienceWe demonstrate the results of the first ab initio investigation of the line-shape parameters for two molecular systems important for atmospheric studies CO-N2 and O2-N2. We provide the pressure broadening and shift coefficients with their speed dependencies for purely rotational lines, calculated from highly accurate potential energy surfaces with the close-coupling scheme. This is the first, fully quantum approach to the problem of determination of the spectral line shapes for the systems important for terrestrial atmospheric measurements

Ab initio calculations of collisional line–shape parameters and generalized spectroscopic cross-sections for rovibrational dipole lines in HD perturbed by He

International audienceWe report ab initio calculations of generalized spectroscopic cross-sections for hydrogen deuteride perturbed by helium. From these calculations, collisional line-shape parameters are deduced for the HD electric dipole transitions from R(0) to R(5) and from P(1) to P(6) in the 0–0 to 5–0 bands. These parameters are necessary for a proper interpretation of HD spectra from the atmospheres of gas giants. We demonstrate that the centrifugal distortion cannot be ignored, not only for pure rotational lines but also for rovibrational lines when one aims at sub–percent accuracy of the collisional line–shape parameters

Fully quantum calculations of O2-N2 scattering using a new potential energy surface: Collisional perturbations of the oxygen 118 GHz fine structure line

International audienceA proper description of the collisional perturbation of the shapes of molecular resonances is important for remote spectroscopic studies of the terrestrial atmosphere. Of particular relevance are the collisions between the O2 and N2 molecules—the two most abundant atmospheric species. In this work, we report a new highly accurate potential energy surface and use it for performing the first quantum scattering calculations addressing line shapes for this system. We use it to model the shape of the 118 GHz fine structure line in O2 perturbed by collisions with N2 molecules, a benchmark system for testing our methodology in the case of an active molecule in a spin triplet state. The calculated collisional broadening of the line agrees well with the available experimental data over a wide temperature range relevant for the terrestrial atmosphere. This work constitutes a step toward populating the spectroscopic databases with ab initio line shape parameters for atmospherically relevant systems. © 2021 Author(s)

Confrontation of the molecular hydrogen spectra in the presence of noble gases with ab initio calculation

International audienceHydrogen molecule in its ground electronic state perturbed by the helium atom constitutes the simplest system of molecule perturbed by atom. This gives possibility to make a link between the experiment and the theory from the first principles, allowing to use ab initio calculations to make the physical interpretation of the experimental spectra.1 This also gives an opportunity to thoroughly study collisional line-shape effects on both experimental and theoretical ground.2We utilize highly accurate cavity ring-down spectroscopy1,2 to study the H2-He collisions and interactions.3 In contrast to most of the previous studies, we do not fit spectra with phenomenological line shapes, but directly superimpose theoretical profiles on the raw experimental spectra without fitting any of the line-shape parameters. Within this approach not only the shapes of experimental lines are reliably reproduced, but also the underlying physics of molecular collisions can be traced.Besides the analysis of the basic line-shape effects (such as relaxation or phase changes of the internal states of the molecule), we also analyse the more sophisticated ones such as speed-dependent effects or velocity-changing collisions (complex Dicke parameter)4,5, which are particularly pronounced for the H2-He system.3,6,7,8According to our knowledge, this is the first comparison of highly accurate experimental spectra with advanced ab initio models which includes the speed-dependent effects and velocity-changing collisions. It allows us to study quantum scattering for molecules as well as to validate ab initio quantum potentials in ranges very challenging for quantum chemistry method

Confrontation of the molecular hydrogen spectra in the presence of noble gases with ab initio calculation

International audienceHydrogen molecule in its ground electronic state perturbed by the helium atom constitutes the simplest system of molecule perturbed by atom. This gives possibility to make a link between the experiment and the theory from the first principles, allowing to use ab initio calculations to make the physical interpretation of the experimental spectra.1 This also gives an opportunity to thoroughly study collisional line-shape effects on both experimental and theoretical ground.2We utilize highly accurate cavity ring-down spectroscopy1,2 to study the H2-He collisions and interactions.3 In contrast to most of the previous studies, we do not fit spectra with phenomenological line shapes, but directly superimpose theoretical profiles on the raw experimental spectra without fitting any of the line-shape parameters. Within this approach not only the shapes of experimental lines are reliably reproduced, but also the underlying physics of molecular collisions can be traced.Besides the analysis of the basic line-shape effects (such as relaxation or phase changes of the internal states of the molecule), we also analyse the more sophisticated ones such as speed-dependent effects or velocity-changing collisions (complex Dicke parameter)4,5, which are particularly pronounced for the H2-He system.3,6,7,8According to our knowledge, this is the first comparison of highly accurate experimental spectra with advanced ab initio models which includes the speed-dependent effects and velocity-changing collisions. It allows us to study quantum scattering for molecules as well as to validate ab initio quantum potentials in ranges very challenging for quantum chemistry method

The ab initio dataset of H 2 -He line-shape parameters for the HITRAN database with the DPL temperature dependences

International audienc

The first comprehensive dataset of beyond-Voigt line-shape parameters from ab initio quantum scattering calculations for the HITRAN database: He-perturbed H2 case study

We demonstrate a new method for populating line-by-line spectroscopic databases with beyond-Voigt line-shape parameters, which is based on ab initio quantum scattering calculations. We report a comprehensive dataset for the benchmark system of He-perturbed H2 (we cover all the rovibrational bands that are present in the HITRAN spectroscopic database). We generate the entire dataset of the line-shape parameters (broadening and shift, their speed dependence, and the complex Dicke parameter) from fully ab initio quantum-scattering calculations. We extend the previous calculations by taking into account the centrifugal distortion for all the bands and by including the hot bands. The results are projected on a simple structure of the quadratic speed-dependent hard-collision profile. We report a simple and compact formula that allows the speed-dependence parameters to be calculated directly from the generalized spectroscopic cross sections. For each line and each line-shape parameter, we provide a full temperature dependence within the double-power-law (DPL) representation, which makes the dataset compatible with the HITRAN database. The temperature dependences cover the range from 20 to 10 0 0 K, which includes the low temperatures relevant for the studies of the atmospheres of giant planets. The final outcome from our dataset is validated on highly accurate experimental spectra collected with cavity ring-down spectrometers. The methodology can be applied to many other molecular species important for atmospheric and planetary studies

The ab initio dataset of H 2 -He line-shape parameters for the HITRAN database with the DPL temperature dependences

International audienc