Impact of graphene-molecular interaction on collective orientation barrier for organic film growth

2021 ◽  
Author(s):  
Sae Nagai ◽  
Yuta Inaba ◽  
Toshio Nishi ◽  
Shigetaka Tomiya
Keyword(s):  
Temperature Regime ◽  
Molecular Interaction ◽  
Energy Barrier ◽  
Molecular Orientation ◽  
Film Growth ◽  
Organic Film ◽  
Temperature Dependent ◽  
Collective Orientation ◽  
Substrate Interaction

Abstract The temperature-dependent molecular orientation variation of pentacene (PEN) on a graphene-covered substrate (PEN/Gr) was investigated via p-polarized multiple-angle incidence resolution spectrometry (pMAIRS). The temperature regime of the orientation transition of PEN/Gr was different from that of PEN/SiO2. The collective orientation barrier (COB), an energy barrier that molecules need to overcome to form a standing orientation, was estimated via pMAIRS. Consequently, the COB of PEN/Gr was found to be 10 times larger than that of PEN/SiO2. This indicated that the COB is valuable for understanding the effect of substrate interaction on the molecular orientation.

scholarly journals Direct observation of epitaxial organic film growth: temperature-dependent growth mechanisms and metastability

2015 ◽  
Vol 17 (43) ◽  
pp. 29150-29160 ◽  
Author(s):  
Helder Marchetto ◽  
Thomas Schmidt ◽  
Ullrich Groh ◽  
Florian C. Maier ◽  
Pierre L. Lévesque ◽  
...  
Keyword(s):  
Direct Observation ◽  
Growth Temperature ◽  
Film Growth ◽  
Growth Dynamics ◽  
Organic Films ◽  
Growth Mechanisms ◽  
Organic Film ◽  
Temperature Dependent ◽  
Dependent Growth

Growth dynamics and structures of organic films, and hence their properties, strongly depend on temperature and substrate morphology, as shown for the example PTCDA on Ag(111).

Steps in Organic Film Growth

Science ◽  
2008 ◽  
Vol 321 (5885) ◽  
pp. 12e-12e
Keyword(s):  
Film Growth ◽  
Organic Film

A study of conformation about the aryl C-N bonds in N-aryl imides by dynamic N.M.R. spectroscopy

1976 ◽  
Vol 29 (2) ◽  
pp. 295 ◽  
Author(s):  
SM Verma ◽  
NB Singh
Keyword(s):  
Energy Barrier ◽  
Phenyl Group ◽  
Spectral Studies ◽  
Free Rotation ◽  
Conformational Study ◽  
Temperature Dependent ◽  
Restricted Rotation ◽  
Planar Conformation

A series of α, β-(9,10-dihydroanthracene-9,10-diyl)-N-arylsuccinimide derivatives has been prepared and their N.M.R. spectral studies are reported. The effect of the substituents at the N-phenyl group on the conformational process about the aryl C-N bond has been investigated.The asymmetric cage moiety present in this system was employed for the conformational study.� The N.M.R. spectra provided evidence for the non-planar conformation and restricted rotation about the aryl C-N bond in the case of ortho-substituted derivatives. Electronegative substituents were found to have a preferred conformation (anti to the cage moiety). The energy barrier (ΔGt) of the order of 86 kJ/mol has been determined by their temperature-dependent spectra. Free rotation about the aryl C-N bond was observed for the meta- and para-substituted derivatives. No buttressing effect by meta substituents has been noticed.

scholarly journals Experimental and computational evaluation of the barrier to torsional rotation in a butadiyne-linked porphyrin dimer

2016 ◽  
Vol 18 (7) ◽  
pp. 5264-5274 ◽  
Author(s):  
Martin D. Peeks ◽  
Patrik Neuhaus ◽  
Harry L. Anderson
Keyword(s):  
Absorption Spectrum ◽  
Energy Barrier ◽  
Temperature Dependent ◽  
Computational Evaluation ◽  
Nir Absorption ◽  
Torsional Rotation ◽  
Porphyrin Dimer

Temperature-dependent changes in the UV-vis-NIR absorption spectrum of a butadiyne linked porphyrin dimer have been used to determine the height of the energy barrier to torsional rotation.

Nucleation, growth, and aggregation of gold on polyimide surfaces

1999 ◽  
Vol 14 (9) ◽  
pp. 3673-3683 ◽  
Author(s):  
Y. Travaly ◽  
L. Zhang ◽  
Y. Zhao ◽  
R. Pfeffer ◽  
K. Uhrich ◽  
...  
Keyword(s):  
Room Temperature ◽  
Film Growth ◽  
Contact Angles ◽  
Thin Film Growth ◽  
Hole Filling ◽  
Temperature Dependent ◽  
Au Film ◽  
The Stability ◽  
Pi System ◽  
Thermal Stability Of

The growth of ultrathin gold films on polyimide (PI) surfaces and the stability of the films upon thermal annealing have been studied using a combination of various techniques. With scanning electron microscopy (SEM) we observe that, at room temperature, the Au film initially grows by nucleation of compact Au islands. With increasing metal coverage, the clusters partially agglomerate to produce a wormlike structure. Finally, percolation, hole-filling, and continuous thin-film growth are observed. To evaluate the thermal stability of the Au/PI system, annealing at various temperatures was performed on films that displayed the wormlike structure. SEM results indicate strong temperature-dependent changes in film morphology. Finally, from our SEM data we determine contact angles, allowing us to estimate interfacial and adhesion energies.

scholarly journals Enhancing the Inhomogeneonus Photodynamics of Canonical Bacteriophytochrome

2021 ◽  
Author(s):  
Jakub Rydzewski ◽  
Katarzyna Walczewska-Szewc ◽  
Sylwia Czach ◽  
Marco Caricato ◽  
Sijin Ren ◽  
...  
Keyword(s):  
Energy Barrier ◽  
Deinococcus Radiodurans ◽  
Metastable States ◽  
Signal Transduction Pathways ◽  
Nanometer Scale ◽  
Thermal Transition ◽  
Enhanced Sampling ◽  
Temperature Dependent ◽  
Dark Reversion ◽  
First Time

The ability of phytochromes to act as photoswitches in plants and microorganisms depends on interactions between a bilin-like chromophore and a protein. The interconversion occurs between the spectrally distinct red (Pr) and far-red (Pfr) conformers. This conformational change is triggered by the photoisomerization of the chromophore D-ring pyrrole. In this study, as a representative example of a phytochrome-bilin system, we take biliverdin IXα (BV) bound to bacteriophytochrome (BphP) from Deinococcus radiodurans. In the absence of light, we use an enhanced sampling molecular dynamics (MD) method to overcome the photoisomerization energy barrier. We find that the calculated free energy (FE) barriers between essential metastable states agree with spectroscopic results. We show that the enhanced dynamics of the BV chromophore in BphP triggers nanometer-scale conformational movements that propagate by two experimentally determined signal transduction pathways. Most importantly, we describe how the metastable states enable a thermal transition known as the dark reversion between Pfr and Pr, through a previously unknown intermediate state of Pfr. Here, for the first time, the heterogeneity of temperature-dependent Pfr states is presented at the atomistic level. This work paves a way toward understanding the complete mechanism of the photoisomerization of a bilin-like chromophore in phytochromes.

scholarly journals Small-Polaron Hopping and Low-Temperature (45–225 K) Photo-Induced Transient Absorption in Magnesium-Doped Lithium Niobate

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 809
Author(s):  
Simon Messerschmidt ◽  
Andreas Krampf ◽  
Laura Vittadello ◽  
Mirco Imlau ◽  
Tobias Nörenberg ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Temperature Regime ◽  
Transient Absorption ◽  
Small Polaron ◽  
Good Representation ◽  
Temperature Dependent ◽  
Polaron Hopping ◽  
Two Parameters ◽  
Oppositely Charged ◽  
Small Polarons

A strongly temperature-dependent photo-induced transient absorption is measured in 6.5 mol% magnesium-doped lithium niobate at temperatures ranging from 45 K to 225 K. This phenomenon is interpreted as resulting from the generation and subsequent recombination of oppositely charged small polarons. Initial two-photon absorptions generate separated oppositely charged small polarons. The existence of these small polarons is monitored by the presence of their characteristic absorption. The strongly temperature-dependent decay of this absorption occurs as series of thermally assisted hops of small polarons that facilitate their merger and ultimate recombination. Our measurements span the high-temperature regime, where small-polaron jump rates are Arrhenius and strongly dependent on temperature, and the intermediate-temperature regime, where small-polaron jump rates are non-Arrhenius and weakly dependent on temperature. Distinctively, this model provides a good representation of our data with reasonable values of its two parameters: Arrhenius small-polaron hopping’s activation energy and the material’s characteristic phonon frequency.

A B.F.S. Method Survey of Surface and Interfacial Properties of Multicomponent Metallic Systems

1997 ◽  
Vol 492 ◽  
Author(s):  
G. Bozzolo ◽  
J. Ferrante ◽  
B. Good
Keyword(s):  
Thin Film ◽  
Film Growth ◽  
Thin Film Growth ◽  
Current Status ◽  
Surface Alloying ◽  
Atomic Processes ◽  
Bulk Materials ◽  
Temperature Dependent ◽  
Surface Energies ◽  
Physical Foundation

ABSTRACTComputer modeling of atomic processes on surfaces and bulk materials has seen noticeable growth due to the availability of new, powerful semiempirical techniques that provide both the numerical simplicity, physical foundation and computational efficiency necessary for the study of complex systems. In an attempt to partially summarize the current status of this work, we apply one of these techniques, the BFS method for alloys, to the study of several basic topics in surface structure and analysis: surface energies of alloy surfaces, multilayer relaxation of ordered alloy surfaces, temperature-dependent segregation profiles, surface alloying and thin film growth of multicompo-nent systems.

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