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  • 1
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    Measuring the charge state of an adatom with noncontact atomic force microscopy (2009)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2009-06-13
    Description: Charge states of atoms can be investigated with scanning tunneling microscopy, but this method requires a conducting substrate. We investigated the charge-switching of individual adsorbed gold and silver atoms (adatoms) on ultrathin NaCl films on Cu(111) using a qPlus tuning fork atomic force microscope (AFM) operated at 5 kelvin with oscillation amplitudes in the subangstrom regime. Charging of a gold atom by one electron charge increases the force on the AFM tip by a few piconewtons. Moreover, the local contact potential difference is shifted depending on the sign of the charge and allows the discrimination of positively charged, neutral, and negatively charged atoms. The combination of single-electron charge sensitivity and atomic lateral resolution should foster investigations of molecular electronics, photonics, catalysis, and solar photoconversion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gross, Leo -- Mohn, Fabian -- Liljeroth, Peter -- Repp, Jascha -- Giessibl, Franz J -- Meyer, Gerhard -- New York, N.Y. -- Science. 2009 Jun 12;324(5933):1428-31. doi: 10.1126/science.1172273.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉IBM Research, Zurich Research Laboratory, 8803 Ruschlikon, Switzerland. lgr@zurich.ibm.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19520956" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    The chemical structure of a molecule resolved by atomic force microscopy (2009)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2009-08-29
    Description: Resolving individual atoms has always been the ultimate goal of surface microscopy. The scanning tunneling microscope images atomic-scale features on surfaces, but resolving single atoms within an adsorbed molecule remains a great challenge because the tunneling current is primarily sensitive to the local electron density of states close to the Fermi level. We demonstrate imaging of molecules with unprecedented atomic resolution by probing the short-range chemical forces with use of noncontact atomic force microscopy. The key step is functionalizing the microscope's tip apex with suitable, atomically well-defined terminations, such as CO molecules. Our experimental findings are corroborated by ab initio density functional theory calculations. Comparison with theory shows that Pauli repulsion is the source of the atomic resolution, whereas van der Waals and electrostatic forces only add a diffuse attractive background.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gross, Leo -- Mohn, Fabian -- Moll, Nikolaj -- Liljeroth, Peter -- Meyer, Gerhard -- New York, N.Y. -- Science. 2009 Aug 28;325(5944):1110-4. doi: 10.1126/science.1176210.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉IBM Research, Zurich Research Laboratory, 8803 Ruschlikon, Switzerland. lgr@zurich.ibm.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19713523" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Bond-order discrimination by atomic force microscopy (2012)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2012-09-18
    Description: We show that the different bond orders of individual carbon-carbon bonds in polycyclic aromatic hydrocarbons and fullerenes can be distinguished by noncontact atomic force microscopy (AFM) with a carbon monoxide (CO)-functionalized tip. We found two different contrast mechanisms, which were corroborated by density functional theory calculations: The greater electron density in bonds of higher bond order led to a stronger Pauli repulsion, which enhanced the brightness of these bonds in high-resolution AFM images. The apparent bond length in the AFM images decreased with increasing bond order because of tilting of the CO molecule at the tip apex.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gross, Leo -- Mohn, Fabian -- Moll, Nikolaj -- Schuler, Bruno -- Criado, Alejandro -- Guitian, Enrique -- Pena, Diego -- Gourdon, Andre -- Meyer, Gerhard -- New York, N.Y. -- Science. 2012 Sep 14;337(6100):1326-9. doi: 10.1126/science.1225621.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉IBM Research-Zurich, CH-8803 Ruschlikon, Switzerland. lgr@zurich.ibm.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22984067" target="_blank"〉PubMed〈/a〉
    Keywords: Carbon Monoxide/*chemistry ; Copper/chemistry ; Electrons ; Microscopy, Atomic Force ; Molecular Structure ; Polycyclic Compounds/chemistry ; Polycyclic Hydrocarbons, Aromatic/*chemistry ; Sodium Chloride/chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    Noncoding RNA. piRNA-guided slicing specifies transcripts for Zucchini-dependent, phased piRNA biogenesis (2015)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2015-05-16
    Description: In animal gonads, PIWI-clade Argonaute proteins repress transposons sequence-specifically via bound Piwi-interacting RNAs (piRNAs). These are processed from single-stranded precursor RNAs by largely unknown mechanisms. Here we show that primary piRNA biogenesis is a 3'-directed and phased process that, in the Drosophila germ line, is initiated by secondary piRNA-guided transcript cleavage. Phasing results from consecutive endonucleolytic cleavages catalyzed by Zucchini, implying coupled formation of 3' and 5' ends of flanking piRNAs. Unexpectedly, Zucchini also participates in 3' end formation of secondary piRNAs. Its function can, however, be bypassed by downstream piRNA-guided precursor cleavages coupled to exonucleolytic trimming. Our data uncover an evolutionarily conserved piRNA biogenesis mechanism in which Zucchini plays a central role in defining piRNA 5' and 3' ends.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mohn, Fabio -- Handler, Dominik -- Brennecke, Julius -- New York, N.Y. -- Science. 2015 May 15;348(6236):812-7. doi: 10.1126/science.aaa1039.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Dr. Bohrgasse 3, 1030 Vienna, Austria. ; Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Dr. Bohrgasse 3, 1030 Vienna, Austria. julius.brennecke@imba.oeaw.ac.at.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25977553" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Drosophila Proteins/genetics/*metabolism ; Drosophila melanogaster/*enzymology/genetics ; Endoribonucleases/genetics/*metabolism ; Evolution, Molecular ; Female ; Germ Cells/enzymology ; Male ; Mice ; Ovary/enzymology ; *RNA Cleavage ; RNA, Guide/*metabolism ; RNA, Small Interfering/biosynthesis/*metabolism ; RNA-Binding Proteins/genetics ; Testis/enzymology ; *Transcription, Genetic ; Uridine/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
    Electronic Resource
    Electronic Resource
    Kationische Farbstoffe und Vorstufen. XVI. Styrylcyanine der 1,3-Oxathiolium-Reihe (1972)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 314 (1972), S. 419-427 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In einer Einstufenreaktion werden 1,3-Oxathiolium-styrylcyanine 7 bzw. 8 aus aromatischen Aldehyden, N,N-disubstituierten Alkylthioamiden und Phenacylhalogeniden bzw. p-Chinonen hergestellt. Ein möglicher Cyanin-Bildungsmechanismus wird diskutiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19723140305
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    Paper (German National Licenses)
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  • 6
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    piRNA-guided slicing specifies transcripts for Zucchini-dependent, phased piRNA biogenesis (2015)
    American Association for the Advancement of Science
    Details
    Publication Date: 2015-05-14
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science
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