Scanning Kelvin microscopy as a tool for visualization of optically induced molecular switching in azobenzene self assembling films

Stiller, B.; Karageorgiev, Peter; Perez-Enciso, E.; Vélez, Marisela; Vieira, S.; Reiche, J.; Knochenhauer, Gerald; Prescher, Dietrich; Brehmer, L.

doi:10.1002/1096-9918(200008)30:1<549::aid-sia776>3.0.co;2-k

Cited by 11 publications

(17 citation statements)

References 15 publications

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“…Modification of the electrical properties of the aligning films under irradiation was studied by Kelvin probe technique dealing with surface potential çp 16,17 this method the investigated films are deposited onto the conductive layers used as the earthed electrodes in the electrical circuit. We applied ITO and Au coatings as conductive substrates for PVCN layers.…”

Section: Methodsmentioning

confidence: 99%

Surface electrical potential of the aligning polymer substrates and dielectric properties of LC layers

Kravchuk¹,

Yaroshchuk²,

Koval’chuk³

et al. 2002

Selected Papers From the International Conference on Spectroscopy of Molecules and Crystals

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UV light influence on the surface potential s of poly(vinylcinnamate) (PVCN) layers widely used for liquid crystal (LC) photoalignment is investigated. In case when PVCN film is spin coated on the ITO electrodes the surface potential changes under irradiation in both PVCN aligning film and ITO coating. The measured increment of the surface potential s=400 mV is mainly caused by the photoconductivity of ITO electrodes, whereas the part caused by PVCN substrate is at least one order of magnitude lower. The relaxation time of s for the ITO-PVCN coatings was estimated to be about 1 h. The induced potential may substantially modify dielectric properties of the aligned LC layers and its anchoring characteristics when the freshly irradiated substrates are used. On the contrary, this influence is weak when the substrates are irradiated several hours before the use for LC alignment

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Section: Methodsmentioning

confidence: 99%

Surface electrical potential of the aligning polymer substrates and dielectric properties of LC layers

Kravchuk¹,

Yaroshchuk²,

Koval’chuk³

et al. 2002

Selected Papers From the International Conference on Spectroscopy of Molecules and Crystals

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“…Although scanning probe microscopy itself is not able to visualize the process of molecular isomerization or reorientation, it is often used for visualization and inspection of the inscribed nano‐ and micro‐structures (Stiller et al ., 2000, 2001). In this study we have used atomic force microscopy (AFM) not only to visualize the photoinduced structures but also to detect mechanical changes of the optically modulated film surface.…”

Section: Introductionmentioning

confidence: 99%

Optical patterning in azobenzene polymer films

Stiller

Geue

Morawetz

et al. 2005

Journal of Microscopy

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SummaryThin azobenzene polymer films show a very unusual property, namely optically induced material transport. The underlying physics for this phenomenon has not yet been thoroughly explained. Nevertheless, this effect enables one to inscribe different patterns onto film surfaces, including one-and two-dimensional periodic structures. Typical sizes of such structures are of the order of micrometers, i.e. related to the interference pattern made by the laser used for optical excitation. In this study we have measured the mechanical properties of one-and two-dimensional gratings, with a high lateral resolution, using force -distance curves and pulse force mode of the atomic force microscope. We also report on the generation of considerably finer structures, with a typical size of 100 nm, which were inscribed onto the polymer surface by the tip of a scanning near-field optical microscope used as an optical pen. Such inscription not only opens new application possibilities but also gives deeper insight into the fundamentals physics underlying optically induced material transport.

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“…[1][2][3][4] Their electronic and thermal properties make them promising molecular moieties for optical molecular switches, optoelectronic and nonlinear optical applications, as well as for sensors. [1][2][3][4] Combined with the potential of SAMs to modify surfaces, such azobenzene functionalized systems represent invaluable model systems of biological and technological interest. SAMs of alkanethiols are among the most intensively studied systems as they can be easily bound to several relatively inert metal surfaces (e.g., Au, Ag) via reaction with the thiol group.…”

Section: Introductionmentioning

confidence: 99%

“…This process is reversible, and irradiation with 450 nm light, corresponding to the absorption maximum for the reverse transformation, almost entirely reestablishes the initial film configuration. [2][3][4] This back-and-forth switching has been recently demonstrated by directly measuring the surface potential change over several switching cycles using the Kelvin probe method. 4 The difference in surface potential between the two isomers is related to the net change of the molecular dipole moment (normal component with respect to the surface).…”

Section: Introductionmentioning

confidence: 99%

Photoemission from Azobenzene Alkanethiol Self-Assembled Monolayers

Weber¹,

Winter²,

Hertel³

et al. 2003

J. Phys. Chem. B

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Photoelectron spectra were measured for films of self-assembled azobenzene-terminated alkanethiol monolayers on gold using synchrotron radiation. The azobenzene was substituted either by CF 3 or CH 3 in the para position. As a result of the orientational order of the molecules within the films, as indicated by the pronounced angle dependence of the photoemission spectra, it is possible to identify laser-induced optical switching of the molecules using combined laser and synchrotron pulses. Molecular switching, i.e., photoisomerization, is recognized by relative intensity changes of the photoemission peaks and also by spectral shifts to higher binding energies. The latter result from a change of the molecular dipole moment associated with the transcis laser-induced photoisomerization of the azobenzene-CF 3 group.

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Scanning Kelvin microscopy as a tool for visualization of optically induced molecular switching in azobenzene self assembling films

Cited by 11 publications

References 15 publications

Surface electrical potential of the aligning polymer substrates and dielectric properties of LC layers

Surface electrical potential of the aligning polymer substrates and dielectric properties of LC layers

Optical patterning in azobenzene polymer films

Photoemission from Azobenzene Alkanethiol Self-Assembled Monolayers

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