L'etude numerique du comportement d'un panache gazeux et d'un nano-agregat crees lors l'ablation laser par impulsions. courtes est etudiee par la methode de dynamique moleculaire. Lors de l'evolution d'une nanoparticule, deux phenomenes coexistent: l'agglomeration (ou agregation) et l'evaporation. La temperature seuil de la nanoparticule a partir de laquelle l'evaporation predomine est ainsi determinee. La presence du panache gazeux modifie ce comportement. D'autre part la condensation de ce gaz est un parametre non negligeable dans la poursuite de cette etude.
{"title":"Évolution temporelle des agrégats créés par impulsions laser courtes : évaporation et condensation","authors":"Karine Gouriet, Tatiana Itina, Leonid V. Zhigilei","doi":"10.1051/JP4:2006138010","DOIUrl":"https://doi.org/10.1051/JP4:2006138010","url":null,"abstract":"L'etude numerique du comportement d'un panache gazeux et d'un nano-agregat crees lors l'ablation laser par impulsions. courtes est etudiee par la methode de dynamique moleculaire. Lors de l'evolution d'une nanoparticule, deux phenomenes coexistent: l'agglomeration (ou agregation) et l'evaporation. La temperature seuil de la nanoparticule a partir de laquelle l'evaporation predomine est ainsi determinee. La presence du panache gazeux modifie ce comportement. D'autre part la condensation de ce gaz est un parametre non negligeable dans la poursuite de cette etude.","PeriodicalId":14838,"journal":{"name":"Journal De Physique Iv","volume":"1 1","pages":"83-88"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87790650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Le code de calcul de profils de raie PPP a ete developpe a l'origine avec l'objectif de synthetiser les raies spectrales emises par les plasmas et ce pour n'importe quel emetteur et n'importe quelles conditions de plasmas. Les motivations de ce travail ont ete d'une part le diagnostic et d'autre part les etudes de la dynamique non lineaire des charges dans les plasmas. Le code numerique base sur des modeles originaux met en jeu des algorithmes qui realisent le meilleur compromis entre precision et rapidite. En particulier, le mouvement des charges perturbatrices est pris en compte par le Modele de Fluctuation de Frequences qui transforme le profil statique en profil dynamique. Ce code a ete sans cesse ameliore au cours des dix dernieres annees avec l'aide d'une technique de simulation numerique basee sur la methode de dynamique moleculaire qui fournit des profils dits de reference.
{"title":"Modélisation des profils de raie dans les plasmas : PPP -nouvelle version","authors":"Annette Calisti, S. Ferri, C. Mossé","doi":"10.1051/JP4:2006138012","DOIUrl":"https://doi.org/10.1051/JP4:2006138012","url":null,"abstract":"Le code de calcul de profils de raie PPP a ete developpe a l'origine avec l'objectif de synthetiser les raies spectrales emises par les plasmas et ce pour n'importe quel emetteur et n'importe quelles conditions de plasmas. Les motivations de ce travail ont ete d'une part le diagnostic et d'autre part les etudes de la dynamique non lineaire des charges dans les plasmas. Le code numerique base sur des modeles originaux met en jeu des algorithmes qui realisent le meilleur compromis entre precision et rapidite. En particulier, le mouvement des charges perturbatrices est pris en compte par le Modele de Fluctuation de Frequences qui transforme le profil statique en profil dynamique. Ce code a ete sans cesse ameliore au cours des dix dernieres annees avec l'aide d'une technique de simulation numerique basee sur la methode de dynamique moleculaire qui fournit des profils dits de reference.","PeriodicalId":14838,"journal":{"name":"Journal De Physique Iv","volume":"1 1","pages":"95-103"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79849362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ERCA students have the opportunity to use one of the main European-based astronomical observing facilities: the "Observatoire de Haute Provence"but before a general presentation of astronomy and astrophysics is necessary. Because astronomy is an old science, starting from history is determinant. Observation tools, i.e. telescopes but also data analysis tools, are presented here as they are presented during on-site courses. This paper can be used by students before courses, for a better preparation during observations with telescopes, but also after courses, for better completion of their formation.
{"title":"Astronomical observations with OHP telescopes","authors":"J. Patris, A. Sarkissian","doi":"10.1051/JP4:2006139024","DOIUrl":"https://doi.org/10.1051/JP4:2006139024","url":null,"abstract":"ERCA students have the opportunity to use one of the main European-based astronomical observing facilities: the \"Observatoire de Haute Provence\"but before a general presentation of astronomy and astrophysics is necessary. Because astronomy is an old science, starting from history is determinant. Observation tools, i.e. telescopes but also data analysis tools, are presented here as they are presented during on-site courses. This paper can be used by students before courses, for a better preparation during observations with telescopes, but also after courses, for better completion of their formation.","PeriodicalId":14838,"journal":{"name":"Journal De Physique Iv","volume":"14 1 1","pages":"373-390"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90458829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Although Venus is often referred to as the most Earth-like of the terrestrial planets, its runaway greenhouse has resulted in a dry, hot, uninhabitable surface. Its surface geology is complex, with volcanoes ranging from 500 km across, lava flows fields >800km across, mountain belts, rift zones, and terrains unique to Venus such as tesserae and coronae. It surface has an average crater retention age similar to Earth's continents, but the random nature of the impact crater population renders it useless in providing time constraints for the geologic history of Venus. At some point in the past, Venus lost an ocean's worth of water. If this water persisted on the surface for long periods of time in Venus's early history, life may have evolved. Untangling, the complex history of Venus, and what it reveals for the evolution of habitable planets, will require future missions to the surface.
{"title":"Venus: Divergent outcomes of terrestrial planet formation","authors":"E. Stofan","doi":"10.1051/JP4:2006139003","DOIUrl":"https://doi.org/10.1051/JP4:2006139003","url":null,"abstract":"Although Venus is often referred to as the most Earth-like of the terrestrial planets, its runaway greenhouse has resulted in a dry, hot, uninhabitable surface. Its surface geology is complex, with volcanoes ranging from 500 km across, lava flows fields >800km across, mountain belts, rift zones, and terrains unique to Venus such as tesserae and coronae. It surface has an average crater retention age similar to Earth's continents, but the random nature of the impact crater population renders it useless in providing time constraints for the geologic history of Venus. At some point in the past, Venus lost an ocean's worth of water. If this water persisted on the surface for long periods of time in Venus's early history, life may have evolved. Untangling, the complex history of Venus, and what it reveals for the evolution of habitable planets, will require future missions to the surface.","PeriodicalId":14838,"journal":{"name":"Journal De Physique Iv","volume":"57 1","pages":"9-19"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84057550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Clouds are the largest uncertainty in future projections of climate. This critically important uncertainty is addressed by studying the role of atmospheric electromagnetics in cloud initiation. Cloud droplets are produced by cloud condensation nuclei. However, the formation of cloud condensation nuclei ultimately relies on physical mechanisms on the atomic and molecular scale which influence the meta-stable phase transition between condensation and evaporation. At these small spatial scales, electrical forces are important. A small yet non-zero influence of electric fields and energetic charged particles on the formation of cloud condensation nuclei would have important consequences for climate change, as small changes in cloud initiation can lead to large changes in global temperature. The current knowledge on the role of atmospheric electromagnetics and energetic charged particles in cloud initiation and climate change is summarised and recommendations for future work are proposed.
{"title":"Atmospheric electromagnetics and climate change","authors":"M. Füllekrug","doi":"10.1051/JP4:2006139011","DOIUrl":"https://doi.org/10.1051/JP4:2006139011","url":null,"abstract":"Clouds are the largest uncertainty in future projections of climate. This critically important uncertainty is addressed by studying the role of atmospheric electromagnetics in cloud initiation. Cloud droplets are produced by cloud condensation nuclei. However, the formation of cloud condensation nuclei ultimately relies on physical mechanisms on the atomic and molecular scale which influence the meta-stable phase transition between condensation and evaporation. At these small spatial scales, electrical forces are important. A small yet non-zero influence of electric fields and energetic charged particles on the formation of cloud condensation nuclei would have important consequences for climate change, as small changes in cloud initiation can lead to large changes in global temperature. The current knowledge on the role of atmospheric electromagnetics and energetic charged particles in cloud initiation and climate change is summarised and recommendations for future work are proposed.","PeriodicalId":14838,"journal":{"name":"Journal De Physique Iv","volume":"13 1","pages":"157-166"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80460441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Lecherbourg, S. Fourmaux, J. Kieffer, F. Martin, H. Pepin, M. Chaker, S. Magnan, C. Cote
Les processus dynamiques se produisant lors de transitions de phase ultra-rapide peuvent etre deduits a partir de mesures de diffraction ou d'absorption de rayonnement X. Les lasers femtosecondes ont recemment ete utilises pour etudier la dynamiques de la matiere au moyen d'une pompe optique et d'une sonde X: du rayonnement X K alpha produit par interaction laser plasma. Nous presentons nos plus recents resultats concernant le developpement d'un syteme de spectroscopie d'absorption du rayonnement X (XAS) basee sur une source laser-plasma large bande dans la gamme 1-5 nm permettant d'atteindre une resolution temporelle femtoseconde. Le systeme est concu pour sonder les dynamiques electroniques ayant lieu durant la transion de phase semiconducteur-metal du dyoxide de vanadium (V02) lorsque celle-ci est initiee par une impulsion laser femtoseconde. Dans la presente experience, un spectre large bande proche du seuil L du vanadium (511 eV) et du seuil K de l'oxygene (525 eV) du V02 a ete genere et mesure avec un haut rapport signal sur bruit (100), une grande resolution spectrale (AE/E = 4.2 x 10 -3 ), et une resolution temporelle de 1,2 ps.
时所产生的动态过程,高速相位跃迁可以线上付款措施起了衍射X射线激光器femtosecondes或吸收了最近被用于研究通过泵领域的动态和光学探针X: K - X光辐射的阿尔法收益的激光等离子体相互作用。本文介绍了基于1-5 nm范围内的宽带激光等离子体源的X射线吸收光谱(XAS)系统的最新成果，该系统能够实现飞秒时间分辨率。该系统旨在探测由飞秒激光脉冲引起的二氧化钒(V02)半导体金属相变过程中的电子动力学。presente体验中,一位接近贫困线的宽带频谱贫困线511钒的L (eV)和氧(525号V02 eV) K a ete genere和测量与高噪声信号报告(100),一个高光谱分辨率(ae2005 / E = 4.2×10 - 3)和一个时间分辨率的1.2倍ps。
{"title":"Source X-UV pour la spectroscopie d'absorption en régime femtoseconde","authors":"L. Lecherbourg, S. Fourmaux, J. Kieffer, F. Martin, H. Pepin, M. Chaker, S. Magnan, C. Cote","doi":"10.1051/JP4:2006138008","DOIUrl":"https://doi.org/10.1051/JP4:2006138008","url":null,"abstract":"Les processus dynamiques se produisant lors de transitions de phase ultra-rapide peuvent etre deduits a partir de mesures de diffraction ou d'absorption de rayonnement X. Les lasers femtosecondes ont recemment ete utilises pour etudier la dynamiques de la matiere au moyen d'une pompe optique et d'une sonde X: du rayonnement X K alpha produit par interaction laser plasma. Nous presentons nos plus recents resultats concernant le developpement d'un syteme de spectroscopie d'absorption du rayonnement X (XAS) basee sur une source laser-plasma large bande dans la gamme 1-5 nm permettant d'atteindre une resolution temporelle femtoseconde. Le systeme est concu pour sonder les dynamiques electroniques ayant lieu durant la transion de phase semiconducteur-metal du dyoxide de vanadium (V02) lorsque celle-ci est initiee par une impulsion laser femtoseconde. Dans la presente experience, un spectre large bande proche du seuil L du vanadium (511 eV) et du seuil K de l'oxygene (525 eV) du V02 a ete genere et mesure avec un haut rapport signal sur bruit (100), une grande resolution spectrale (AE/E = 4.2 x 10 -3 ), et une resolution temporelle de 1,2 ps.","PeriodicalId":14838,"journal":{"name":"Journal De Physique Iv","volume":"1 1","pages":"63-72"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83819334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ocean can be considered as a chemical reactor, whose energy sources are the various matter inputs originating from the continent and the ocean. Among various elements, carbon plays a key role as it is involved in both inorganic form as CO 2 and organic forms such as compounds synthesized through photosynthesis. Thus, the ocean is presently an active actor in climate change and ocean-atmosphere exchange processes. This review will present some insights into: 1) schematic representations of the carbon cycle, with emphasis on CO 2 exchange between the ocean and the atmosphere and to the organic parts of this cycle, 2) concepts relative to the biological pump of CO 2 , with a detailed view on photosynthesis, 3) concepts leading to the existence of oceanic provinces and associated productivity for open sea and coastal areas, 4) addressing the question: what is the net efficiency of the biological pump of CO 2 in terms of exportation of organic carbon and sequestration in sediments and 5) specific aspects on biogeochemical processes occurring at the boundary between the ocean and the atmosphere.
{"title":"Biogeochemical processes in the ocean and at the ocean-atmosphere interface","authors":"A. Saliot","doi":"10.1051/JP4:2006139015","DOIUrl":"https://doi.org/10.1051/JP4:2006139015","url":null,"abstract":"The ocean can be considered as a chemical reactor, whose energy sources are the various matter inputs originating from the continent and the ocean. Among various elements, carbon plays a key role as it is involved in both inorganic form as CO 2 and organic forms such as compounds synthesized through photosynthesis. Thus, the ocean is presently an active actor in climate change and ocean-atmosphere exchange processes. This review will present some insights into: 1) schematic representations of the carbon cycle, with emphasis on CO 2 exchange between the ocean and the atmosphere and to the organic parts of this cycle, 2) concepts relative to the biological pump of CO 2 , with a detailed view on photosynthesis, 3) concepts leading to the existence of oceanic provinces and associated productivity for open sea and coastal areas, 4) addressing the question: what is the net efficiency of the biological pump of CO 2 in terms of exportation of organic carbon and sequestration in sediments and 5) specific aspects on biogeochemical processes occurring at the boundary between the ocean and the atmosphere.","PeriodicalId":14838,"journal":{"name":"Journal De Physique Iv","volume":"12 1","pages":"197-209"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87667885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. A. Hernandez-Perez, C. Garapon, Corinne Champeaux, A. W. Coleman, LaureVE Guy
Les potentialites des methodes de depot par ablation laser (PLD) pour la preparation de films minces de materiaux organiques sont illustrees par un bref rappel bibliographique et par des resultats experimentaux concernant des molecules d'interet biologique (acides amines, calix-arenes, proteines). Les films sont prepares par PLD avec un laser KrF sans degradation de la structure chimique des molecules dans une gamme de fluences de quelques dizaines a quelques centaines de mJ/cm 2 . Les proprietes structurales et optiques des films sont etudiees en fonction de la fluence du laser et mettent en evidence des arrangements moleculaires particuliers induits par cette methode de depot. Le guidage optique a ete obtenu pour des films de toutes ces molecules.
{"title":"Élaboration de films de molécules organiques par ablation par laser UV","authors":"M. A. Hernandez-Perez, C. Garapon, Corinne Champeaux, A. W. Coleman, LaureVE Guy","doi":"10.1051/JP4:2006138021","DOIUrl":"https://doi.org/10.1051/JP4:2006138021","url":null,"abstract":"Les potentialites des methodes de depot par ablation laser (PLD) pour la preparation de films minces de materiaux organiques sont illustrees par un bref rappel bibliographique et par des resultats experimentaux concernant des molecules d'interet biologique (acides amines, calix-arenes, proteines). Les films sont prepares par PLD avec un laser KrF sans degradation de la structure chimique des molecules dans une gamme de fluences de quelques dizaines a quelques centaines de mJ/cm 2 . Les proprietes structurales et optiques des films sont etudiees en fonction de la fluence du laser et mettent en evidence des arrangements moleculaires particuliers induits par cette methode de depot. Le guidage optique a ete obtenu pour des films de toutes ces molecules.","PeriodicalId":14838,"journal":{"name":"Journal De Physique Iv","volume":"48 1","pages":"181-190"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79117331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Jamelot, D. Ros, Kevin Cassou, S. Kazamias, A. Klisnick, Michaela Kozlova, Tomas Mocek, P. Homer, Jiri Polan, M. Stupka
Nous presentons des resultats recents concernant des premieres investigations de microscopie interferentielle par laser X-UV d'endommagement optique. Le laser X-UV utilise est un laser collisionnel en regime quasi-stationnaire emettant a 21.2nm, developpe au Prague Asterix Laser System (PALS, Prague, Republique Tcheque). Des echantillons de silice fondue de haute qualite, avec ou sans rayure, etaient irradiees en face avant par un laser bleu, correspondant au 3 eme harmonique du laser a iode du PALS (1.315 μm), servant egalement a realiser le laser X-UV a 21.2 nm. Celui-ci etait utilise, 5 ns apres l'irradiation pour realiser une imagerie microscopique et interferentielle de la face arriere de l'echantillon. Les resultats font apparaitre des deformations locales transitoires. Des premieres analyses mettent en evidence une probable variation de la rugosite de la surface. Cette demonstration experimentale encourageante ouvre la voie a de futures investigations, notamment sur notre prochaine installation laser: LASERIX.
{"title":"Microscopie interférentielle X-UV : un outil pour l'étude des endommagements des surfaces optiques","authors":"G. Jamelot, D. Ros, Kevin Cassou, S. Kazamias, A. Klisnick, Michaela Kozlova, Tomas Mocek, P. Homer, Jiri Polan, M. Stupka","doi":"10.1051/JP4:2006138028","DOIUrl":"https://doi.org/10.1051/JP4:2006138028","url":null,"abstract":"Nous presentons des resultats recents concernant des premieres investigations de microscopie interferentielle par laser X-UV d'endommagement optique. Le laser X-UV utilise est un laser collisionnel en regime quasi-stationnaire emettant a 21.2nm, developpe au Prague Asterix Laser System (PALS, Prague, Republique Tcheque). Des echantillons de silice fondue de haute qualite, avec ou sans rayure, etaient irradiees en face avant par un laser bleu, correspondant au 3 eme harmonique du laser a iode du PALS (1.315 μm), servant egalement a realiser le laser X-UV a 21.2 nm. Celui-ci etait utilise, 5 ns apres l'irradiation pour realiser une imagerie microscopique et interferentielle de la face arriere de l'echantillon. Les resultats font apparaitre des deformations locales transitoires. Des premieres analyses mettent en evidence une probable variation de la rugosite de la surface. Cette demonstration experimentale encourageante ouvre la voie a de futures investigations, notamment sur notre prochaine installation laser: LASERIX.","PeriodicalId":14838,"journal":{"name":"Journal De Physique Iv","volume":"218 1","pages":"245-250"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75611795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This chapter describes the photo-chemical production of aerosol particles in two very different regions of the atmosphere: iodine oxide particles in the marine boundary layer (MBL), and meteoric smoke particles that form in the upper mesosphere from the ablation of interplanetary dust. These two systems are surprisingly analogous - the source of the condensable inorganic vapours is external to the atmosphere, being injected into the atmosphere from the ocean or from space - and the particles are formed by homogeneous nucleation. The purpose of the chapter is to describe a laboratory and modelling study to understand at a fundamental level how the nucleation and growth of the particles occurs. Iodine oxide particles were produced from the photo-oxidation of gaseous I 2 with O 3 , which is most likely the primary photo-chemical route to produce the bursts of new particles observed in the MBL at seaweed-rich coastal locations. The captured particles were observed to be fractal-like (i.e., with open or non-compact structures), and to be composed of the stable oxide I 2 O 5 . Meteoric smoke analogues of iron oxide, silicon oxide, and iron silicate composition were similarly formed from the photo-oxidation of iron- and silicon-containing gas-phase precursors in the presence of O 3 . Imaging of the iron-containing particles showed them to be extended, fractal aggregates. For each system, models were developed to elucidate the growth kinetics of the particles and to characterise them in terms of standard fractal parameters. I 2 O 5 particles were found to have a fractal dimension (D f ) value of 2.5 at long growth times, consistent with a particle-cluster diffusion-limited aggregation (DLA) mechanism, whereas smoke analogues had lower D f values (1.75) which appear to result from a magnetic aggregation process.
{"title":"Inorganic aerosol formation and growth in the Earth's lower and upper atmosphere","authors":"R. Saunders, J. Plane","doi":"10.1051/JP4:2006139017","DOIUrl":"https://doi.org/10.1051/JP4:2006139017","url":null,"abstract":"This chapter describes the photo-chemical production of aerosol particles in two very different regions of the atmosphere: iodine oxide particles in the marine boundary layer (MBL), and meteoric smoke particles that form in the upper mesosphere from the ablation of interplanetary dust. These two systems are surprisingly analogous - the source of the condensable inorganic vapours is external to the atmosphere, being injected into the atmosphere from the ocean or from space - and the particles are formed by homogeneous nucleation. The purpose of the chapter is to describe a laboratory and modelling study to understand at a fundamental level how the nucleation and growth of the particles occurs. Iodine oxide particles were produced from the photo-oxidation of gaseous I 2 with O 3 , which is most likely the primary photo-chemical route to produce the bursts of new particles observed in the MBL at seaweed-rich coastal locations. The captured particles were observed to be fractal-like (i.e., with open or non-compact structures), and to be composed of the stable oxide I 2 O 5 . Meteoric smoke analogues of iron oxide, silicon oxide, and iron silicate composition were similarly formed from the photo-oxidation of iron- and silicon-containing gas-phase precursors in the presence of O 3 . Imaging of the iron-containing particles showed them to be extended, fractal aggregates. For each system, models were developed to elucidate the growth kinetics of the particles and to characterise them in terms of standard fractal parameters. I 2 O 5 particles were found to have a fractal dimension (D f ) value of 2.5 at long growth times, consistent with a particle-cluster diffusion-limited aggregation (DLA) mechanism, whereas smoke analogues had lower D f values (1.75) which appear to result from a magnetic aggregation process.","PeriodicalId":14838,"journal":{"name":"Journal De Physique Iv","volume":"1 1","pages":"239-256"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91531855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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