Artificial Antenna Research Articles

Dendrimers as Controlled Artificial Energy Antennae

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDendrimers as Controlled Artificial Energy AntennaeArie Bar-Haim, Joseph Klafter, and Raoul KopelmanView Author Information School of Chemistry, Tel Aviv University Tel Aviv 69978, Israel Department of Chemistry, University of Michigan Ann Arbor, Michigan 48109-1055 Cite this: J. Am. Chem. Soc. 1997, 119, 26, 6197–6198Publication Date (Web):July 2, 1997Publication History Received27 March 1997Published online2 July 1997Published inissue 1 July 1997https://doi.org/10.1021/ja970972fCopyright © 1997 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views532Altmetric-Citations238LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (165 KB) Get e-AlertsSUBJECTS:Chemical calculations,Chemical structure,Dendrons,Energy,Mathematical methods Get e-Alerts

Spectral properties of the photosynthetic reaction units reconstituted from bacterial reaction centres and antenna pigments located in liposomes suspended in buffer or ordered in Langmuir-Blodgett films

Artificial photosynthetic reaction units reconstituted from photosynthetic bacterial reaction centres and antenna pigments (bacteriochlorophyll a or chlorophyll a) and built in liposome vesicles were investigated. Samples were suspended in buffer or ordered in Langmuir-Blodgett films. The absorption, photoacoustic and delayed luminescence spectra of the liposomes in suspension and in Langmuir-Blodgett films deposited on quartz plates were measured. As a reference, suspensions or films containing reaction centres or antenna pigments only, both embedded in liposomes, were investigated. The absorption spectra of the samples containing reaction centres and pigment mixtures were the sum of the absorptions of samples containing reaction centres and pigments separately. This result shows that, in the mixed sample, strong interactions due to the formation of ground state aggregates are absent. The photoacoustic and absorption spectra are different because of the different yield of thermal deactivation of various chromphores. The yield of thermal deactivation of the pigments in reaction centres is higher than that of additional artificial antenna molecules. This yield is at least partially due to the rather efficient excitation energy transfer from the antenna to reaction centres competing with the thermal deactivation of excitation. All samples exhibit a delayed luminescence with the spectra located in the spectral regions of the prompt fluorescence of the investigated pigments. A comparison of the intensity of delayed luminescence of the artificial photoreaction unit with the intensities of reference samples demonstrates that excitation energy transfer from the antenna to the chromophores of the reaction centres occurs. In liposome suspensions and in monolayers, the absorption spectra of the samples containing reaction centres and pigment mixtures are similar, but the photoacoustic spectra and delayed luminescence spectra are different. This shows that the mutual interactions between the reaction centre chromophores and antenna pigments in liposomes located in suspensions and in monolayers are different.

人工能動触角 対象物の曲率の影響について

The Artificial Active Antenna is the sensor system motivated by the insect's antenna. It can detect the location between an insensitive flexible beam and an object through measurement of the rotational compliance on the beam in contact with the object. The goal of this paper is to consider the effects of the environment curvature on the sensing accuracy. We first introduce a set of basic equations representing force-deformation and geometrical relationships. Both numerical and approximate solutions are shown with experimental results. We show that the effect of the environment curvature on the sensing accuracy can be discussed by usung one non-dimensional parameter consisting of the pushing angle, the contact distance, and the radius of curvature of the object. Finally, we show that the environment curvature makes little influence on the sensing accuracy.

ビジョンベースト人工能動触角

ビジョンベースト人工能動触角

Cationic dye molecules in zeolite L as artificial antenna

The antenna behaviour of oxonine and pyronine loaded zeolite L microcrystals is investigated. The geometrical constraints of this system exclude aggregation and therefore self quenching of electronic excitation energy even at very high concentration and lead to a highly anisotropic antenna system based on Forster energy transfer. Microcrystals with size of the order of 100 to 200 nm are found to be optimal for realising an efficient light harvesting antenna. Solvatochromy is shown to be a useful tool to distinguish between dye molecules on the surface and inside of zeolite L microcrystals. The method is expected to be applicable to other zeolite/dye systems also.

95/06651 Dye molecules in zeolites as artificial antenna

95/06651 Dye molecules in zeolites as artificial antenna

A robot with the aim of an organism. Challenge an active and artificial antenna.

A robot with the aim of an organism. Challenge an active and artificial antenna.

Dye molecules in zeolites as artificial antenna

When cationic dye molecules are exchanged into the parallel channels of zeolite L, they are so close together that energy transfer can occur. The restricted geometry of the zeolite L channels excludes aggregation and self-quenching even at very high concentration. We report three types of experiments with pyronine and oxonine which indicate that such zeolite-dye arrangements can be used as antenna for light harvesting. First, we show that energy transfer occurs inside the zeolite microcrystals filled with a mixture of both chromophores. This proves that the achieved distance distribution fulfils the conditions imposed by the law of electronic excitation energy transfer. Second, we show that the quanta absorbed by pyronine located inside the zeolite microcrystals can be trapped by an acceptor with the right spectral properties placed on their surface. In a third experiment, we show that in a mixture of zeolite microcrystals loaded with pyronine as donor D and others loaded with oxonine as acceptor A, energy transfer occurs from the D to the A filled particles.

Harvesting sunlight by artificial supramolecular antennae

We have designed a divergent synthetic strategy, based on the “complexes-as-metals and complexes-as-ligands” procedure, to prepare polynuclear metal compounds of nanometer size and dendritic structure. Such a synthetic strategy is modular, very flexible, efficient, and characterized by a full, step-by-step control of the growing process. It allows us to obtain supramolecular arrays where different metal ions, bridging ligands, and terminal ligands can occupy predetermined sites. In this way, the light absorption, luminescence, and redox properties of these polynuclear compounds can be varied. In particular, it is possible to obtain a synthetic control of the direction(s) of electronic energy transfer after light absorption. This is a step towards the construction of nanometer-sized antennae for harvesting solar energy.

Beamwidth of a Line Source Excited Artificial Dielectric Antenna

Radiation characteristics of an artificial dielectric antenna excited by a line source are described. Analytical expressions for the half power beamwidth are obtained for odd and even modes. Results for beamwidth calculated from these expressions are in good agreement with the values of beamwidth obtained from the radiation pattern.

Frequency scanning by leaky-wave antennas using artificial dielectrics

Frequency-scanning characteristics of an artificial dielectric leaky-wave antenna are discussed. It is experimentally observed that the beam angle changes from 10\deg to 50\deg off broadside when the frequency is changed from 8.13 to 9.05 GHz. Over this frequency range the beamwidth does not vary monotonically and changes from 7.5\deg to 6.0\deg to 7.1\deg . It is found that the artificial dielectric antenna has a better temperature stability than that for frequency scanned arrays.

Harmonic Oscillations in Directly Excited Antennas Used in Radio Telegraphy

Using a symmetrically excited artificial antenna consisting of two long coils with a spark gap between them, the author measures the frequencies, decrements, and the relative amplitudes of the fundamental current and of each of the harmonics. It is found that the theoretical rectangular wave, travelling along the antenna, is modified in form, particularly if the spark is fairly persistent. Numerical data are given.

Some Experiments with Long Electrical Conductors

Working at frequencies from 12 to 152 cycles per second, an artificial antenna made up of numerous sections each having lumped capacity and inductance (and closely simulating an actual antenna), is carefully studied. The effective capacity, inductance, and resistance are measured and found to agree with theory; and the theoretical effects of capacity and inductance loading are similarly experimentally verified.

The Effect of a Parallel Condenser in the Receiving Antenna

Tuning inductances placed in artificial and actual antennae are shunted by a tuning condenser. In all cases the introduction of this capacity is found to reduce the strength of received signals.

Editorial notes [on "A discussion on experimental tests of the radiation law for radio oscillators"

The three principal methods in use at the present time for determining "radiation resistance," arranged in order of increasing precision, are the following: (a) Inserting in the ground connection of the antenna a noninductive resistance of such value that the current in the antenna is diminished in the ratio of one to the square root of two The additional resistance is then taken as equal to the non-conservative "radiation resistance." (b) Determining from the resonance cuirve of the antenna by the Bjerknes method the damping factor and calculating therefrom the apparent "radiation resistance." (c) Replacing the antenna by an artificial antenna of i(lentical effective inductance and capacity, and ascertaining what noninductive resistance must be inserted in the artificial antenna to secure in it the same current as formerly flowed in the actual antenna. We have appended for the convenience of the reader the following list of important articles and references dealing with this matter.