@article{VollmerMoellmann2008, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Infrarotkameras: es gibt mehr zu sehen als unsere Augen wahrnehmen}, series = {In: Naturwissensschaftliche Rundschau 61 (2008) 11, 557—565}, journal = {In: Naturwissensschaftliche Rundschau 61 (2008) 11, 557—565}, pages = {557 -- 565}, year = {2008}, language = {de} } @article{VollmerMoellmannArnold2008, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter and Arnold, Frank}, title = {Ins eigene Segel blasen. M{\"u}nchhausen-Effekt und Schubumkehr}, series = {In: Physik in unserer Zeit 39 (2008) 5, 241-245}, journal = {In: Physik in unserer Zeit 39 (2008) 5, 241-245}, doi = {10.1002/piuz.200801172}, pages = {241 -- 245}, year = {2008}, abstract = {Kann man sich mit seinem Segelboot fortbewegen, indem man ins eigene Segel bl{\"a}st? Der Impulssatz erlaubt diesen an M{\"u}nchhausen erinnernden Effekt. Das demonstriert ein vereinfachtes Gedankenexperiment, bei dem der Segler durch den Werfer eines Balls und das Segel durch eine starre Wand ersetzt wird. Allerdings ergibt die naive Theorie, die Luftmolek{\"u}le als ball{\"a}hnliche Korpuskeln auffasst, einen zu hohen Impuls des reflektierten Luftstroms. Eine realistische Beschreibung liefert die moderne Str{\"o}mungstheorie. Ihre Resultate sind experimentell erfolgreich umsetzbar. Technisch angewendet wird das Prinzip in der Schubumkehr von Flugzeugtriebwerken.}, language = {de} } @incollection{ChiaverinaVollmer2006, author = {Chiaverina, Chris and Vollmer, Michael}, title = {Learning physics from the experiments}, series = {In: Informal learning and public understanding of physics : third international GIREP seminar 2005 ; selected contributions ; [5 - 9 September 2005, Ljubljana, Slovenia] / ed.: Gorazd Planinšič ... Ljubljana : Faculty of Mathematics and Physics, 2006}, booktitle = {In: Informal learning and public understanding of physics : third international GIREP seminar 2005 ; selected contributions ; [5 - 9 September 2005, Ljubljana, Slovenia] / ed.: Gorazd Planinšič ... Ljubljana : Faculty of Mathematics and Physics, 2006}, publisher = {Faculty of Mathematics and Physics}, address = {Ljubljana}, year = {2006}, language = {en} } @article{Vollmer2005, author = {Vollmer, Michael}, title = {Diffraction revisited : position of diffraction spots upon rotation of a transmission grating}, series = {In: Physics education 40 (2005), 562-565}, journal = {In: Physics education 40 (2005), 562-565}, pages = {562 -- 565}, year = {2005}, language = {en} } @article{Vollmer2005, author = {Vollmer, Michael}, title = {Hot gases : transition from line spectra to thermal radiation}, series = {In: American journal of physics 73 (2005), 215-223}, journal = {In: American journal of physics 73 (2005), 215-223}, pages = {215 -- 223}, year = {2005}, abstract = {The question of how the line spectrum of atoms is transformed into the continuous spectrum of thermal radiation of a gas by repeated absorption and emission of photons is addressed. We consider a simple model of a hydrogen-like gas in thermal equilibrium where only the Lyman-α transition is allowed and calculate the spectra for increasing thickness of the gas. The transition from line spectra for optically thin samples to the spectra of thermal radiation for optically thick samples is demonstrated. We estimate the emissivities for hot gases and study the line width of spectral lines due to self-absorption processes.}, language = {en} } @article{CowleyLavenVollmer2005, author = {Cowley, L. and Laven, Ph. and Vollmer, Michael}, title = {Rings around sun and moon : coronae and diffraction}, series = {In: Physics Education 40 (2005) 1, 51-59}, journal = {In: Physics Education 40 (2005) 1, 51-59}, pages = {51 -- 59}, year = {2005}, language = {en} } @article{VollmerMoellmannKarstaedt2004, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter and Karst{\"a}dt, Detlef}, title = {Microwave oven experiments with metals and light sources}, series = {In: Physics Education 39 (2004), 500-508}, journal = {In: Physics Education 39 (2004), 500-508}, pages = {500 -- 508}, year = {2004}, abstract = {Don't put metal objects in the microwave' is common safety advice. But why? Here we describe demonstration experiments involving placing household metallic objects in a microwave oven. These allow a better understanding of the interaction of microwaves with materials. Light bulbs and discharge lamps can also be used in instructive demonstrations.}, language = {en} } @article{VollmerMoellmannKarstaedt2004, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter and Karst{\"a}dt, Detlef}, title = {More experiments with microwave ovens}, series = {In: Physics education 39 (2004) 4, 346 - 351}, journal = {In: Physics education 39 (2004) 4, 346 - 351}, pages = {346 -- 351}, year = {2004}, abstract = {Microwave ovens can be used to perform exciting demonstrations that illustrate a variety of physics topics. Experiments discussed here show superheating, visualize the inhomogeneous heating that takes place in a microwave and also show how to use a mobile phone to detect radiation leaking from the oven. Finally eggs can give some spectacular (though messy) explosions. In all cases please note the safety advice given.}, language = {en} } @article{ParkerVollmer2004, author = {Parker, Kerry and Vollmer, Michael}, title = {Bad food and good physics : the development of domestic microwave cookery}, series = {In: Physics Education 39 (2004) 1, 82-90}, journal = {In: Physics Education 39 (2004) 1, 82-90}, pages = {82 -- 90}, year = {2004}, abstract = {This article forms the second of two papers on the subject of microwave cookers. In the first paper Michael Vollmer describes the physics behind the production of microwaves in the magnetron of the oven, the waveguide and the interaction between the microwaves and the food. This article looks at the physics of cooking, and how the appliance and the food industries have developed products which are now part of many of our students' lifestyles. We include many interesting demonstrations that illustrate this history and which could be used to teach many principles of physics.}, language = {en} } @article{Vollmer2004, author = {Vollmer, Michael}, title = {Physics of the microwave oven}, series = {In: Physics education 39 (2004) 1, 74-81}, journal = {In: Physics education 39 (2004) 1, 74-81}, pages = {74 -- 81}, year = {2004}, abstract = {This is the first of two articles about the physics of microwave ovens. This article deals with the generation of microwaves in the oven and includes the operation of the magnetrons, waveguides and standing waves in resonant cavities. It then considers the absorption of microwaves by foods, discussing the dielectric relaxation of water, penetration depths of electromagnetic waves in matter and, in considering the possible chemical changes during the microwave heating, multi-photon ionization or dissociation.}, language = {en} } @article{Vollmer2003, author = {Vollmer, Michael}, title = {Physics teacher training and research in physics education: results of an inquiry by the European Physical Society}, series = {In: European journal of physics 24 (2003), 131-147}, journal = {In: European journal of physics 24 (2003), 131-147}, pages = {131 -- 147}, year = {2003}, abstract = {An inquiry among national experts on physics education research and teaching has been carried out using a questionnaire that deals with the organization of physics teacher training and the main tasks and research activities of professionals in physics education. The goal was to collect data on a European scale on physics teacher training at universities by professionals as well as on research activities by professionals in the field of physics education. Results are presented based on answers from 22 European countries.}, language = {en} } @article{Vollmer2003, author = {Vollmer, Michael}, title = {Estimating the thickness of the atmosphere by rayleigh scattering}, series = {In: American journal of physics 71 (2003) 10, 979-983}, journal = {In: American journal of physics 71 (2003) 10, 979-983}, pages = {979 -- 983}, year = {2003}, language = {en} } @article{MoellmannVollmer2000, author = {M{\"o}llmann, Klaus-Peter and Vollmer, Michael}, title = {Eine etwas andere, physikalische Sehweise - Visualisierung von Energieumwandlungen und Strahlungsphysik f{\"u}r die (Hochschul-)lehre}, series = {In: Physikalische Bl{\"a}tter 56 (2000) 9, 65-69}, journal = {In: Physikalische Bl{\"a}tter 56 (2000) 9, 65-69}, doi = {10.1002/phbl.20000560915}, pages = {65 -- 69}, year = {2000}, abstract = {Max Planck legte 1900 mit dem nach ihm benannten Strahlungsgesetz das quantitative Fundament zu so genannten W{\"a}rmebildsystemen. 100 Jahre sp{\"a}ter gibt es — mit bedingt durch Fortschritte in der Halbleitertechnologie und Mikrosystemtechnik — Infrarotkameras, mit denen sowohl die von Planck untersuchten Strahlungsgesetze zur Hohlraumstrahlung als auch allgemein wissenschaftliche und technische Anwendungen der Temperaturstrahlung von K{\"o}rpern untersucht werden k{\"o}nnen. Dar{\"u}ber hinaus bieten sich solche Systeme auch f{\"u}r didaktische Zwecke an, da physikalische Gesetzm{\"a}ßigkeiten mit Energieaustauschprozesssen aus sehr vielen Gebieten der Physik durch eine etwas andere, physikalische Sehweise visualisiert und damit f{\"u}r Lehrzwecke eingesetzt werden k{\"o}nnen.}, language = {de} } @article{MoellmannVollmer2000, author = {M{\"o}llmann, Klaus-Peter and Vollmer, Michael}, title = {Zauberei, Diffusion, industrielle Messtechnik und 100 Jahre Quantentheorie : Einige Freihandexperimente zur Optik und W{\"a}rmestrahlung}, series = {In: Physik in der Schule 38 (2000) 4, 260-262}, journal = {In: Physik in der Schule 38 (2000) 4, 260-262}, pages = {260 -- 262}, year = {2000}, language = {de} } @article{Vollmer2000, author = {Vollmer, Michael}, title = {Unschuldige Schule! : In den vergangenen Jahren hat zwar die Zahl der Physikstudenten dramatisch abgenommen, nicht aber die Zahl der Sch{\"u}ler, die in der Oberstufe Physik w{\"a}hlen}, series = {In: Physikalische Bl{\"a}tter 56 (2000) 6, 21-22}, journal = {In: Physikalische Bl{\"a}tter 56 (2000) 6, 21-22}, doi = {10.1002/phbl.20000560606}, pages = {21 -- 22}, year = {2000}, language = {de} } @article{Vollmer1999, author = {Vollmer, Michael}, title = {Physikalische Texte zum Thema Atmosph{\"a}rische Optik}, series = {In: Meteorologischer Kalender 2000(1999)}, journal = {In: Meteorologischer Kalender 2000(1999)}, year = {1999}, language = {de} } @article{Vollmer2000, author = {Vollmer, Michael}, title = {Das ist ein seltsam wunderbares Zeichen! Ein Streifzug durch die Kulturgeschichte des Regenbogens}, series = {In: Naturwissenschaftliche Rundschau 53 (2000), 497 - 511}, journal = {In: Naturwissenschaftliche Rundschau 53 (2000), 497 - 511}, pages = {497 -- 511}, year = {2000}, language = {de} } @article{Vollmer2000, author = {Vollmer, Michael}, title = {Nach der Sonnenfinsternis in Deutschland: ein Nachschlag und Ausblick (auch) f{\"u}r die Schule}, series = {In: Physik in der Schule 38 (2000) 1, 50-54}, journal = {In: Physik in der Schule 38 (2000) 1, 50-54}, pages = {50 -- 54}, year = {2000}, language = {de} } @article{KarstaedtPinnoMoellmannetal.1999, author = {Karst{\"a}dt, Detlef and Pinno, Frank and M{\"o}llmann, Klaus-Peter and Vollmer, Michael}, title = {Anschauliche W{\"a}rmelehre im Unterricht : ein Beitrag zur Visualisierung thermischer Vorg{\"a}nge}, series = {In:: Praxis der Naturwissenschaften / Physik 48 (1999) 5, 24-31}, journal = {In:: Praxis der Naturwissenschaften / Physik 48 (1999) 5, 24-31}, pages = {24 -- 31}, year = {1999}, language = {de} } @article{VollmerMoellmann1999, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Beispiele physikalischer Freihand- und Low-Cost-Experimente in der Schule}, series = {In: Physik in der Schule 37 (1999) 5, 332-336}, journal = {In: Physik in der Schule 37 (1999) 5, 332-336}, pages = {332 -- 336}, year = {1999}, language = {de} } @article{Vollmer1999, author = {Vollmer, Michael}, title = {Motivation und Stellenwert physikalischer Freihand- und Low-Cost-Experimente in der Schule}, series = {In: Physik in der Schule 37 (1999) 3, 187-192}, journal = {In: Physik in der Schule 37 (1999) 3, 187-192}, pages = {187 -- 192}, year = {1999}, language = {de} } @article{Vollmer1998, author = {Vollmer, Michael}, title = {Gespiegelt in besondern D{\"u}ften …: Oasen, Seeungeheuer und weitere Spielereien der Fata Morgana}, series = {In: Physikalische Bl{\"a}tter 54 (1998) 10, 903-909}, journal = {In: Physikalische Bl{\"a}tter 54 (1998) 10, 903-909}, doi = {.1002/phbl.19980541006}, pages = {903 -- 909}, year = {1998}, abstract = {„Wer die Natur liebt, der braucht das Beobachten ihrer Erscheinungen wie die Luft zum Atmen." — So formulierte Marcel Minnaert das Bed{\"u}rfnis der Naturbeobachtung im Vorwort seines ber{\"u}hmten Buchs „Licht und Farbe in der Natur" [1]. Bekannte Beispiele f{\"u}r Naturerscheinungen in der Atmosph{\"a}re sind Luftspiegelungen, Regenb{\"o}gen und Halos. Diese optischen Ph{\"a}nomene bieten nicht nur faszinierende Anblicke, sondern beinhalten auch gen{\"u}gend Aspekte f{\"u}r eine interessante Physik (z. B. [2]). — Der vorliegende Artikel geht von grundlegenden physikalischen Betrachtungen aus und zeigt, daß sich alle Ph{\"a}nomene atmosph{\"a}rischer Optik {\"u}bersichtlich klassifizieren lassen. Luftspiegelungen werden exemplarisch im Detail behandelt. Viele n{\"u}tzliche Informationen findet man in Standardwerken [1, 3-5]; den aktuellen Stand der Forschung in Konferenzberichten, z. B. [6].}, language = {de} } @article{GedzelmanVollmer2009, author = {Gedzelman, S. D. and Vollmer, Michael}, title = {Twice in a blue moon}, series = {In: Weatherwise 62 (2009) 5, 28-35}, journal = {In: Weatherwise 62 (2009) 5, 28-35}, issn = {0043-1672}, pages = {28 -- 35}, year = {2009}, language = {en} } @article{Vollmer2009, author = {Vollmer, Michael}, title = {Newton´s law of cooling revisited}, series = {In: European Journal of Physics 30 (2009), 1063-1084}, journal = {In: European Journal of Physics 30 (2009), 1063-1084}, issn = {0143-0807}, pages = {1063 -- 1084}, year = {2009}, language = {en} } @article{GedzelmanVollmer2009, author = {Gedzelman, S. D. and Vollmer, Michael}, title = {Progress in atmospheric optics and light and color in nature}, series = {In: Bulletin of the American Meteorological Society : BAMS 90 (2009), 689-693}, journal = {In: Bulletin of the American Meteorological Society : BAMS 90 (2009), 689-693}, issn = {0003-0007}, pages = {689}, year = {2009}, language = {en} } @article{Vollmer2009, author = {Vollmer, Michael}, title = {Mirrors in the Air: Mirages in Nature and in the Laboratory}, series = {In: Physics Education 44 (2009) 2, 165-174}, journal = {In: Physics Education 44 (2009) 2, 165-174}, issn = {0031-9120}, pages = {165 -- 174}, year = {2009}, language = {en} } @article{VollmerMoellmann2008, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Michelson Interferometer for your kitchen table}, series = {In: The Physics Teacher 46 (2008), 114-117}, journal = {In: The Physics Teacher 46 (2008), 114-117}, issn = {0031-921x}, pages = {114 -- 117}, year = {2008}, language = {en} } @article{PlaninsicVollmer2008, author = {Planinsic, G. and Vollmer, Michael}, title = {The surface to volume ratio in thermal physics: from cheese cube physics to animal metabolism}, series = {In: European Journal of Physics 29 (2008), 369-384}, journal = {In: European Journal of Physics 29 (2008), 369-384}, issn = {0143-0807}, pages = {369 -- 384}, year = {2008}, language = {en} } @article{VollmerMoellmannArnold2007, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter and Arnold, F.}, title = {Locomotion by blowing into the sail of a sailboat? From a basic physics question to thrust reversal of jet airplanes}, series = {In: Physics Education 42 (2007), 369-377}, journal = {In: Physics Education 42 (2007), 369-377}, issn = {0031-9120}, pages = {369 -- 377}, year = {2007}, language = {en} } @article{VollmerMoellmann2007, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Infrared thermal imaging as a tool in university physics education}, series = {In: European Journal of Physics 28 (2007), S37-S50}, journal = {In: European Journal of Physics 28 (2007), S37-S50}, pages = {37 -- 50}, year = {2007}, language = {en} } @article{MoellmannVollmer2006, author = {M{\"o}llmann, Klaus-Peter and Vollmer, Michael}, title = {Measurements and predictions of the illuminance during a solar eclipse}, series = {In: European journal of physics 27 (2006), 1299-1314}, journal = {In: European journal of physics 27 (2006), 1299-1314}, pages = {1299 -- 1314}, year = {2006}, abstract = {Measurements of illuminance during a solar eclipse are presented. The data are compared to theoretical predictions, based on a geometrical model for obscuration. The model assumes a straight and uniform motion of the sun and moon as well as a spherical shape of both, i.e. it neglects any effects of limb darkening. Furthermore, the sun's disk is assumed to have homogeneous luminosity, i.e. any luminosity variations due to sun spots are neglected. Input parameters are the duration of the eclipse, the duration of totality, the impact parameter, i.e. the distance between the two trajectories of sun and moon, and the sizes of sun and moon. The model applies to all types of eclipses, partial, annular and total.}, language = {en} } @article{VollmerGedzelman2006, author = {Vollmer, Michael and Gedzelman, S. D.}, title = {Colors of the sun and moon : the role of the optical air mass}, series = {In: European journal of physics 27 (2006), 299-309}, journal = {In: European journal of physics 27 (2006), 299-309}, pages = {299 -- 309}, year = {2006}, abstract = {A geometric model for the optical air mass of the atmosphere is developed. Using the model, simple formulae are derived for the optical thickness of light passing through (1) a molecular atmosphere, (2) an atmosphere with uniformly distributed tropospheric aerosols and (3) atmospheres with elevated aerosol layers. The formulae are used to model the spectra and perceived colours of the Sun and Moon.}, language = {en} } @article{Vollmer1999, author = {Vollmer, Michael}, title = {Naturwissenschaftler auf Banknoten}, series = {In: Physik in unserer Zeit 30 (1999) 3, 114-117}, journal = {In: Physik in unserer Zeit 30 (1999) 3, 114-117}, doi = {10.1002/piuz.19990300305}, pages = {114 -- 117}, year = {1999}, abstract = {Portr{\"a}ts von Naturwissenschaftlern und sachliche Darstellungen aus der Physik finden sich in zahlreichen Bereichen des t{\"a}glichen Lebens, insbesondere auch auf vielen Banknoten. Die Auswahl -- vorgegeben durch die politisch inspirierte Motivwahl der Notenbanken -- stellt eine interessante Reise durch die Wissenschaftsgeschichte dar.}, language = {de} } @article{Vollmer2001, author = {Vollmer, Michael}, title = {Strahlungsgesetz und Augenempfindlichkeit: Bemerkungen zu einer klassischen Fehlinterpretation}, series = {In: Der mathematische und naturwissenschaftliche Unterricht : MNU 54 (2001) 4, 196-200}, journal = {In: Der mathematische und naturwissenschaftliche Unterricht : MNU 54 (2001) 4, 196-200}, pages = {196 -- 200}, year = {2001}, language = {de} } @article{Vollmer1997, author = {Vollmer, Michael}, title = {Der Regenbogen : Vorschlag zur Gestaltung einer interdisziplin{\"a}ren Unterrichtseinheit}, series = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 7, 36-38}, journal = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 7, 36-38}, pages = {36 -- 38}, year = {1997}, language = {de} } @article{VollmerVollmer1997, author = {Vollmer, J. and Vollmer, Michael}, title = {Am Himmel geschehen Zeichen und Wunder : Aberglauben und Bauernregeln bei optischen Erscheinungen der Atmosph{\"a}re}, series = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 3, 31-37}, journal = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 3, 31-37}, pages = {31 -- 37}, year = {1997}, language = {de} } @article{TammerTraenkleKarstaedtetal.1997, author = {Tammer, R. and Tr{\"a}nkle, E. and Karst{\"a}dt, Detlef and Vollmer, Michael}, title = {Spektakel bei Sonnenschein : Lichts{\"a}ulen, Sonnenhunde und und und ...}, series = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 3, 24-30}, journal = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 3, 24-30}, pages = {24 -- 30}, year = {1997}, language = {de} } @article{TammerVollmer1997, author = {Tammer, R. and Vollmer, Michael}, title = {Regenb{\"o}gen in Wasser und edleren Tropfen}, series = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 3, 15-23}, journal = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 3, 15-23}, pages = {15 -- 23}, year = {1997}, language = {de} } @article{Vollmer1997, author = {Vollmer, Michael}, title = {Lichtbrechung, Oasen und Luftschl{\"o}sser: Gibt es den Palast der Fata Morgana ?}, series = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 3, 10-15}, journal = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 3, 10-15}, pages = {10 -- 15}, year = {1997}, language = {de} } @article{Vollmer1997, author = {Vollmer, Michael}, title = {Von den Ph{\"a}nomenen zur Physik: Atmosph{\"a}rische Optik in der Schule}, series = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 3, 2-9}, journal = {In: Praxis der Naturwissenschaften / Physik 46 (1997) 3, 2-9}, pages = {2 -- 9}, year = {1997}, language = {de} } @article{Vollmer1995, author = {Vollmer, Michael}, title = {"Wenn das Licht in Farben sich erbricht ...", Teil 1}, series = {In: : Physik in unserer Zeit 26 (1995) 3, 106 - 115}, journal = {In: : Physik in unserer Zeit 26 (1995) 3, 106 - 115}, doi = {10.1002/piuz.19950260303}, pages = {106 -- 115}, year = {1995}, abstract = {Fata Morgana, Regenb{\"o}gen, Sonnenhunde, Brockengespenst, gr{\"u}ne Sonnenstrahlen, D{\"a}mmerungsfarben bei klarer und tr{\"u}ber Atmosph{\"a}re. Diese optischen Erscheinungen der Atmosph{\"a}re bieten nicht nur faszinierende Anblicke, sondern beinhalten vor allem interessante Physik.}, language = {de} } @article{Vollmer1995, author = {Vollmer, Michael}, title = {"Wenn das Licht in Farben sich erbricht ...", Teil 2}, series = {In: Physik in unserer Zeit 26 (1995) 4, 176 - 184}, journal = {In: Physik in unserer Zeit 26 (1995) 4, 176 - 184}, doi = {10.1002/piuz.19950260406}, pages = {176 -- 184}, year = {1995}, language = {de} } @article{SchneiderVollmer2005, author = {Schneider, Werner B. and Vollmer, Michael}, title = {Experimental simulations of pollen coronas}, series = {In: Applied optics 44 (2005) 27, 5746-5753}, journal = {In: Applied optics 44 (2005) 27, 5746-5753}, doi = {10.1364/AO.44.005746}, pages = {5746 -- 5753}, year = {2005}, abstract = {A procedure to experimentally simulate pollen coronas is discussed. Observed coronas are due to pine and birch pollen having different geometries. Using computer simulations, two-dimensional projections of a large number of pollenlike objects with adjustable shapes, with or without preferential orientation and statistical or regular spatial distribution, are generated. The photograph of the printout allows samples with typical sizes between 20 and 200 µm. Their diffraction patterns can closely resemble the ones observed in nature and predicted by theory. © 2005 Optical Society of America}, language = {en} } @inproceedings{MoellmannLutzVollmeretal.2004, author = {M{\"o}llmann, Klaus-Peter and Lutz, Norbert and Vollmer, Michael and Wille, Ch.}, title = {Thermography of Microsystems}, series = {In: InfraMation proceedings Vol. 5 (2004), 183-196}, booktitle = {In: InfraMation proceedings Vol. 5 (2004), 183-196}, pages = {183 -- 196}, year = {2004}, language = {en} } @article{VollmerGreenler2003, author = {Vollmer, Michael and Greenler, Robert}, title = {More Halo and Mirage Experiments in Atmospheric Optics}, series = {In: Applied Optics 42 (2003) 3, pp. 394-398}, journal = {In: Applied Optics 42 (2003) 3, pp. 394-398}, doi = {10.1364/AO.42.000394}, year = {2003}, abstract = {Some laboratory demonstrations on atmospheric optics are presented. The focus is on dispersion effects in mirages, lateral mirages, and inferior mirages produced with small hot plates. We also show a demonstration of the upper-tangent-arc halo, produced with a hexagonal prism, rotating about two axes. © 2003 Optical Society of America}, language = {en} } @article{VollmerTammer1998, author = {Vollmer, Michael and Tammer, Robert}, title = {Laboratory Experiments in Atmospheric Optics}, series = {In: Applied optics 37 (1998) 9, pp. 1557-1568}, journal = {In: Applied optics 37 (1998) 9, pp. 1557-1568}, doi = {10.1364/AO.37.001557}, pages = {1557 -- 1568}, year = {1998}, abstract = {Old and new laboratory experiments on atmospheric optics with a focus on mirages, rainbows, and halos are presented. Some qualitative demonstrations serve primarily didactical purposes, e.g., by proving the existence of curved light rays in media with a gradient of the index of refraction, by directly visualizing the minimum-deviation curve for rainbow paths in water droplets, or by helping to elucidate the ray classes in hexagons that contribute to a specific halo. In addition, quantitative experiments allow a direct comparison of angular positions and intensities with analytical computations or Monte Carlo simulations of light scattering from small water droplets or ice hexagons. In particular, the latter can help us to understand complex halo phenomena. © 1998 Optical Society of America}, language = {en} } @article{GoetzHoheiselTraegeretal.1995, author = {G{\"o}tz, T. and Hoheisel, W. and Tr{\"a}ger, F. and Vollmer, Michael}, title = {Characterization of Large Supported Metal Clusters by Optical Spectroscopy}, series = {In: Zeitschrift f{\"u}r Physik / D Vol. 33 (1995) 2, pp 133-141}, journal = {In: Zeitschrift f{\"u}r Physik / D Vol. 33 (1995) 2, pp 133-141}, doi = {10.1007/BF01437432}, year = {1995}, abstract = {Small sodium and silver particles were generated on dielectric substrates like LiF, quartz and sapphire under ultrahigh vacuum conditions. The optical transmission spectra of the clusters were measured as a function of cluster size and shape, for low and high substrate temperatures as well as for s- and p- polarization of the incident light. Excitation of dipolar surface plasmon oscillations in the directions normal and parallel to the substrate surface could be identified. Furthermore, optical spectra for Na and Ag clusters were calculated with the classical Mie theory. The measured spectra vary strongly if the experimental conditions are changed and can be exploited, for example, to characterize the particles with regard to their size and shape. In particular, the axial ratio of the spheroidal clusters could be determined. Its value is considerably different for the two investigated metals and depends on the substrate material. Furthermore, the temperature of the substrate has a pronounced influence on the shape of the particles. At low temperature of T=100 K two-dimensional island growth is predominant. The particles extend only little in the direction perpendicular to the surface and coalesce readily at small coverage of metal atoms. In contrast, the clusters are truly three-dimensional at T=300 K. At this stage, sodium particles still exhibit a rather small axial ratio whereas silver clusters appear almost spherical. Thus, measurements of the optical spectra permit direct in situ monitoring of cluster growth during the nucleation of adsorbed atoms and of temperature induced shape variations. In addition to investigations of the shape of the particles, the quadrupolar surface plasmon mode was observed for Ag clusters.}, language = {en} } @inproceedings{Vollmer1994, author = {Vollmer, Michael}, title = {Ablation of Metal Particles with Laser Light: Shape and Polarization Effects}, series = {In: Laser ablation: mechanisms and applications - II : second international conference, Knoxville, TN April 1993 / eds.: John C. Miller ...- New York : American Inst. of Physics, 1994. - (AIP conference proceedings / American Institute of Physics. - Melville, NY, 1970- ; 288) (Laser ablation: mechanisms and applications. - New York : American Institute of Physics ; 2). - S. 32 ff}, booktitle = {In: Laser ablation: mechanisms and applications - II : second international conference, Knoxville, TN April 1993 / eds.: John C. Miller ...- New York : American Inst. of Physics, 1994. - (AIP conference proceedings / American Institute of Physics. - Melville, NY, 1970- ; 288) (Laser ablation: mechanisms and applications. - New York : American Institute of Physics ; 2). - S. 32 ff}, pages = {32 -- 37}, year = {1994}, language = {en} } @article{HoevelFritzHilgeretal.1993, author = {H{\"o}vel, H. and Fritz, S. and Hilger, A. and Kreibig, U. and Vollmer, Michael}, title = {Width of cluster plasmon resonances: Bulk dielectric functions and chemical interface damping}, series = {In: Phys. Rev. B 48 (1993) 24, 18178-18188}, journal = {In: Phys. Rev. B 48 (1993) 24, 18178-18188}, doi = {10.1103/PhysRevB.48.18178}, year = {1993}, abstract = {The damping of collective electron resonances in clusters which develop into plasmon polaritons at larger sizes is investigated for free, supported, and embedded neutral metal clusters. Embedding of free 2 nm Ag clusters of 2-nm diameter into a SiO2 matrix leads to an increase of the width of the resonances by more than a factor of 3. The optical spectra are compared with the Mie theory using size-effect-modified dielectric functions of the solid state. The results corroborate the assumption that the widths of the resonances strongly depend on chemical interface effects. The results are briefly discussed with regard to limited-mean-free-path and quantum-size-effect theories and a recent approach by Persson. It is demonstrated that the widths of the spectra of supported and embedded clusters have to be interpreted with care since true intrinsic size effects of the clusters appear to be less effective than previously believed and can be obscured by the chemical interface damping. © 1993 The American Physical Society}, language = {en} } @article{GoetzTraegerVollmer1993, author = {G{\"o}tz, T. and Tr{\"a}ger, F. and Vollmer, Michael}, title = {Desorption of metal atoms with laser light of different polarization}, series = {In: Applied physics / A 57 (1993) 1, pp 101-104}, journal = {In: Applied physics / A 57 (1993) 1, pp 101-104}, doi = {10.1007/BF00331225}, pages = {101 -- 104}, year = {1993}, abstract = {Laser-induced desorption of metal atoms from the surface of small metal particles has been investigated as a function of the shape of the particles and the polarization of the incident laser light. The particles were supported on LiF, quartz or sapphire substrates. In a first set of experiments, the shape of the particles was determined by recording optical transmission spectra with s- and p-polarized light incident under an angle of typically 40° with respect to the surface normal. The metal particles turn out to be oblate, the ratio of the axes perpendicular and parallel to the substrate surface being on the order of 0.5. This ratio decreases with increasing particle size. Also, the particles change shape if the temperature is raised. In further experiments, s- and p-polarized light has been used to stimulate desorption of atoms via surface plasmon excitation. It is found that the desorption rate markedly depends on the polarization of the light. This is explained by excitation of the collective electron oscillation along different axes of the non-spherical particles.}, language = {en} }