Electronic and vibrational spectra of protonated benzaldehyde-water clusters, [BZ-(H2O)n≤5]H+: evidence for ground-state proton transfer to solvent for n ≥ 3.

International audienceVibrational and electronic photodissociation spectra of mass-selected protonated benzaldehyde-(water)n clusters, [BZ-(H2O)n]H(+) with n ≤ 5, are analyzed by quantum chemical calculations to determine the protonation site in the ground electronic state (S0) and ππ(*) excited state (S1) as a function of microhydration. IR spectra of [BZ-(H2O)n]H(+) with n ≤ 2 are consistent with BZH(+)-(H2O)n type structures, in which the excess proton is localized on benzaldehyde. IR spectra of clusters with n ≥ 3 are assigned to structures, in which the excess proton is located on the (H2O)n solvent moiety, BZ-(H2O)nH(+). Quantum chemical calculations at the B3LYP, MP2, and ri-CC2 levels support the conclusion of proton transfer from BZH(+) to the solvent moiety in the S0 state for hydration sizes larger than the critical value nc = 3. The vibronic spectrum of the S1 ← S0 transition (ππ(*)) of the n = 1 cluster is consistent with a cis-BZH(+)-H2O structure in both electronic states. The large blueshift of the S1 origin by 2106 cm(-1) upon hydration with a single H2O ligand indicates that the proton affinity of BZ is substantially increased upon S1 excitation, thus strongly destabilizing the hydrogen bond to the solvent. The adiabatic S1 excitation energy and vibronic structure calculated at the ri-CC2/aug-cc-pVDZ level agrees well with the measured spectrum, supporting the notion of a cis-BZH(+)-H2O geometry. The doubly hydrated species, cis-BZH(+)-(H2O)2, does not absorb in the spectral range of 23 000-27 400 cm(-1), because of the additional large blueshift of the ππ(*) transition upon attachment of the second H2O molecule. Calculations predict roughly linear and large incremental blueshifts for the ππ(*) transition in [BZ-(H2O)n]H(+) as a function of n. In the size range n ≥ 3, the calculations predict a proton transfer from the (H2O)nH(+) solvent back to the BZ solute upon electronic ππ(*) excitation

Electronic excited state of protonated aromatic molecules: protonated Fluorene

The photo-fragmentation spectrum of protonated fluorene has been recorded in the visible spectral region, largely red shifted as compared to the first excited state absorption of neutral fluorene. The spectrum shows two different vibrational progressions, separated by 0.19 eV that are assigned to the absorption of two isomers. As in protonated linear PAHs, comparison with ab-initio calculations indicates that the red shift is due to the charge transfer character of the excited state

Marketing and Exploitation of Sillar Añashuayco - Arequipa

The Sillar Route is located and developed in the ashlar quarries of Arequipa and is managed by the Ashlar Cutters Association. This research seeks to analyze the social determinants of the viability of sustainable tourism in the Cutters sector of the quarries of Arequipa. ashlar based on the opinion and perception of the quarry workers. The city of Arequipa was distinguished by UNESCO as a Cultural Heritage of Humanity in November 2000, in consideration of the buildings that make up the Cercado in its centuries-old neighborhoods, defined as a Monumental Zone and categorized as: religious monuments, military monuments, monuments civil-public and civil-domestic monuments. All of them share an element that, before the arrival of the conquerors, was already used in buildings built by Andean societies, ashlar. In this article we will see the main input of the buildings that have continued to be used for half a millennium, emerging as a fundamental element of the regional identity and the proposal to value the ashlar quarries, with a thematic tourist route that has been implemented

Caractérisation et dynamique des états excités des molécules aromatiques protonées

Protonated aromatic molecules play an important role in electrophilic aromatic substitution reactions, fundamental reactions in organic chemistry and in various biological processes. The interstellar medium is another environment which is likely to contain the protonated aromatic molecules, that’s because these molecules are stable chemically since they are close shell electronic structure. These molecules were also identified in others environments such as combustion flames, plasmas of various hydrocarbons and the upper atmosphere of Titan. Protonated molecules are usually very sensitive to their local environment; a gas phase study is required to determine their intrinsic properties. Until now, very little is known about the isolated protonated molecules, only a few results are available in the literature. This lack of data is due to the difficulties of the production and the cooling of these molecules in gas phase. The technical progress we have done has enabled the study of protonated molecules in the gas phase at very low temperatures, using an ion sources, supersonic jet and the laser induced photofragmentation techniques. Using this technique, we have recorded many electronic spectra (S1←S0) of different protonated molecules. We can regroup the studied molecules into four: Linear protonated polycyclic aromatic molecules (benzene, naphthalene, anthracene, tetracene, pentacene). Nonlinear protonated polycyclic aromatic molecules (fluorene, phenanthrene, pyrene). Protonated molecules containing an hetero atom (benzaldehyde, salicylaldehyde, 1-naphthol and 2-naphthol, indole, aniline). Protonated cluster (dimer of benzene, naphthalene (H2O)n, n = 1,2,3. Naphthalene (NH3)n, n = 1,2,3, benzaldehyde (Ar, N2)). Most of those spectra are red-shifted compare to the spectrums of neutral parent molecules. This red-shift is due to charge transfer character of the first excited state. Some spectra are vibrationally resolved, while for other molecules the spectrum do not shows any vibrational progression. This behaviour is explained by the dynamic of the excited state, this dynamic being usually is very fast, sometimes leading to the ground state through a conical intersection. The spectra of protonated molecules are very active vibrationally in comparison with neutral molecules, many vibrational modes forbidden for neutral molecule becomes active for the protonated one (Franck-Condon factor is not zero). This is reflecting the charge transfer character of the excited state. The experimental results were complemented by ab-initio calculations, which have allowed determining the electronic transition, the geometric and electronic structure of the molecule, the vibrational modes, and for some of these molecules the dynamics of excited state. Calculations are generally in very good agreement with experiments.Les molécules aromatiques protonées jouent un rôle important dans les réactions de substitution électrophile aromatique, et dans différents processus biologiques. Ces molécules sont présentes aussi dans d’autres milieux tels que les flammes de combustion, les plasmas de divers hydrocarbures, les ionosphères planétaires (Titan) et le milieu interstellaire. Les molécules protonées sont très stables car elles ont des couches électroniques complètes mais elles sont en général très sensibles à leur environnement local car elles sont chargées : une étude en phase gazeuse est nécessaire pour déterminer leurs propriétés intrinsèques. Jusqu’à présent, très peu de chose était connu sur les molécules protonées isolées en phase gazeuse, seulement quelques résultats étaient disponibles. Ce manque de données venait de la difficulté de générer des molécules protonées en phase gazeuse et surtout de les produire à basse température (la protonation est une réaction exothermique). Récemment, des progrès ont permis d’étudier les molécules protonées en phase gazeuse à très basse température, en particulier par le développement des sources ioniques couplées avec des techniques d'expansion de jet supersonique. Grâce à cette technique on a enregistré le spectre photo fragmentation de l’état fondamental vers le premier état excité (S1←S0) de différentes molécules aromatiques protonées en phase gazeuse. Les molécules que nous avons étudiées peuvent être regroupées en quatre familles : Les molécules polycycliques aromatiques protonées linéaires (benzène, naphtalène, anthracène, tétracène, pentacène). Les molécules polycycliques aromatiques protonées non linéaires (fluorène, phénanthrène, pyrène). Les molécules protonées contenant un hétéro atome (benzaldéhyde, salicylaldéhyde, 1-naphthol et 2-naphthol, indole, aniline). Les agrégats protonés (dimère de benzène, naphtalène (H2O)n, n=1,2,3. naphtalène (NH3)n, n=1,2,3, benzaldéhyde (Ar , N2)). Dans les spectres enregistrés presque toutes les transitions électroniques S1←S0 sont décalées vers le rouge (basse énergie) par rapport à celui des molécules parentes neutres. Ce décalage est dû au caractère transfert de charge du premier état excité. Certains spectres sont résolus vibrationnellement, alors que pour d'autres molécules le spectre ne présente pas de progression vibrationnelle à cause d’un dynamique très rapide de l’état excité menant par des intersections coniques à l’état fondamental. Les spectres d’absorption des molécules protonées sont plus riches en vibrations par comparaison avec les molécules neutre. Cela reflète le changement relativement important de géométrie de l’état excité dû à son caractère transfert de charge. Les résultats expérimentaux ont été complétés par des calculs ab-initio qui ont permis de localiser la transition électronique, déterminer la structure géométrique et électronique, les modes de vibration et, pour certaines de ces molécules, la dynamique de l’état excité. Les calculs sont en général en très bon accord avec les expériences

Characterization and dynamics of excited states of protonated aromatic molecules

Les molécules aromatiques protonées jouent un rôle important dans les réactions de substitution électrophile aromatique, et dans différents processus biologiques. Ces molécules sont présentes aussi dans d’autres milieux tels que les flammes de combustion, les plasmas de divers hydrocarbures, les ionosphères planétaires (Titan) et le milieu interstellaire. Les molécules protonées sont très stables car elles ont des couches électroniques complètes mais elles sont en général très sensibles à leur environnement local car elles sont chargées : une étude en phase gazeuse est nécessaire pour déterminer leurs propriétés intrinsèques. Jusqu’à présent, très peu de chose était connu sur les molécules protonées isolées en phase gazeuse, seulement quelques résultats étaient disponibles. Ce manque de données venait de la difficulté de générer des molécules protonées en phase gazeuse et surtout de les produire à basse température (la protonation est une réaction exothermique). Récemment, des progrès ont permis d’étudier les molécules protonées en phase gazeuse à très basse température, en particulier par le développement des sources ioniques couplées avec des techniques d'expansion de jet supersonique. Grâce à cette technique on a enregistré le spectre photo fragmentation de l’état fondamental vers le premier état excité (S1←S0) de différentes molécules aromatiques protonées en phase gazeuse. Les molécules que nous avons étudiées peuvent être regroupées en quatre familles : Les molécules polycycliques aromatiques protonées linéaires (benzène, naphtalène, anthracène, tétracène, pentacène). Les molécules polycycliques aromatiques protonées non linéaires (fluorène, phénanthrène, pyrène). Les molécules protonées contenant un hétéro atome (benzaldéhyde, salicylaldéhyde, 1-naphthol et 2-naphthol, indole, aniline). Les agrégats protonés (dimère de benzène, naphtalène (H2O)n, n=1,2,3. naphtalène (NH3)n, n=1,2,3, benzaldéhyde (Ar , N2)). Dans les spectres enregistrés presque toutes les transitions électroniques S1←S0 sont décalées vers le rouge (basse énergie) par rapport à celui des molécules parentes neutres. Ce décalage est dû au caractère transfert de charge du premier état excité. Certains spectres sont résolus vibrationnellement, alors que pour d'autres molécules le spectre ne présente pas de progression vibrationnelle à cause d’un dynamique très rapide de l’état excité menant par des intersections coniques à l’état fondamental. Les spectres d’absorption des molécules protonées sont plus riches en vibrations par comparaison avec les molécules neutre. Cela reflète le changement relativement important de géométrie de l’état excité dû à son caractère transfert de charge. Les résultats expérimentaux ont été complétés par des calculs ab-initio qui ont permis de localiser la transition électronique, déterminer la structure géométrique et électronique, les modes de vibration et, pour certaines de ces molécules, la dynamique de l’état excité. Les calculs sont en général en très bon accord avec les expériences.Protonated aromatic molecules play an important role in electrophilic aromatic substitution reactions, fundamental reactions in organic chemistry and in various biological processes. The interstellar medium is another environment which is likely to contain the protonated aromatic molecules, that’s because these molecules are stable chemically since they are close shell electronic structure. These molecules were also identified in others environments such as combustion flames, plasmas of various hydrocarbons and the upper atmosphere of Titan. Protonated molecules are usually very sensitive to their local environment; a gas phase study is required to determine their intrinsic properties. Until now, very little is known about the isolated protonated molecules, only a few results are available in the literature. This lack of data is due to the difficulties of the production and the cooling of these molecules in gas phase. The technical progress we have done has enabled the study of protonated molecules in the gas phase at very low temperatures, using an ion sources, supersonic jet and the laser induced photofragmentation techniques. Using this technique, we have recorded many electronic spectra (S1←S0) of different protonated molecules. We can regroup the studied molecules into four: Linear protonated polycyclic aromatic molecules (benzene, naphthalene, anthracene, tetracene, pentacene). Nonlinear protonated polycyclic aromatic molecules (fluorene, phenanthrene, pyrene). Protonated molecules containing an hetero atom (benzaldehyde, salicylaldehyde, 1-naphthol and 2-naphthol, indole, aniline). Protonated cluster (dimer of benzene, naphthalene (H2O)n, n = 1,2,3. Naphthalene (NH3)n, n = 1,2,3, benzaldehyde (Ar, N2)). Most of those spectra are red-shifted compare to the spectrums of neutral parent molecules. This red-shift is due to charge transfer character of the first excited state. Some spectra are vibrationally resolved, while for other molecules the spectrum do not shows any vibrational progression. This behaviour is explained by the dynamic of the excited state, this dynamic being usually is very fast, sometimes leading to the ground state through a conical intersection. The spectra of protonated molecules are very active vibrationally in comparison with neutral molecules, many vibrational modes forbidden for neutral molecule becomes active for the protonated one (Franck-Condon factor is not zero). This is reflecting the charge transfer character of the excited state. The experimental results were complemented by ab-initio calculations, which have allowed determining the electronic transition, the geometric and electronic structure of the molecule, the vibrational modes, and for some of these molecules the dynamics of excited state. Calculations are generally in very good agreement with experiments

A distributed plateform of high interaction honeypots and experimental results (extended version)

International audienceThe increase of various malicious activities spreading on the Internet network are today a crucial problem. In order to understand the motivations and operating modes of the attackers, it is necessary to collect data characterizing these malicious activities. Their analysis enables to better face these attacks, anticipate new threats and better adpat the corresponding protection mechanisms. This paper proposes a distributed platform oh high interaction honeypots deployed for that purpose. The paper describes 1) the design and implementation of this platform, 2) the methodology used to collect and record data characterizing the malicious activities and 3) the first analyses carried out on this data

A distributed plateform of high interaction honeypots and experimental results (extended version)

International audienceThe increase of various malicious activities spreading on the Internet network are today a crucial problem. In order to understand the motivations and operating modes of the attackers, it is necessary to collect data characterizing these malicious activities. Their analysis enables to better face these attacks, anticipate new threats and better adpat the corresponding protection mechanisms. This paper proposes a distributed platform oh high interaction honeypots deployed for that purpose. The paper describes 1) the design and implementation of this platform, 2) the methodology used to collect and record data characterizing the malicious activities and 3) the first analyses carried out on this data

Conformational Study of the Jet-Cooled Diketopiperazine Peptide Cyclo Tyrosyl-Prolyl

International audienceThe conformational landscape of the diketopiperazine (DKP) dipeptide built on tyrosine and proline, namely, cyclo Tyr-Pro, is studied by combining resonance-enhanced multiphoton ionisation, double resonance IR-UV spectroscopy, and quantum chemical calculations. Despite the geometrical constraints due the two aliphatic rings, DKP and proline, cyclo Tyr-Pro is a flexible molecule. For both diastereoisomers, cyclo LTyr-LPro and cylo LTyr-DTyr, two structural families coexist under supersonic jet conditions. In the most stable conformation, the aromatic tyrosine substituent is folded over the DKP ring (g + geometry of the aromatic ring) as it is in the solid state. The other structure is completely extended (g-geometry of the aromatic ring) and resembles that proposed for the vapor phase. IR-UV results are not sufficient for unambiguous assignment of the observed spectra to either folded or extended conformations and the simulation of the vibronic pattern of the S0-S1 transition is necessary. Still, the comparison between IR-UV results and anharmonic calculations allow explaining the minor structural differences between cyclo LTyr-LPro and cylo LTyr-DPro in terms of different NH… and CH… interactions.

Chirality effects in the structures of jet-cooled bichromophoric dipeptides

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