Structure of Normal Alkane Evaporated Films: Molecular Orientation

Nozaki, Koji; Saihara, Rieko; Ishikawa, Kiyoshi; Yamamoto, Takashi

doi:10.1143/jjap.46.761

Cited by 16 publications

(21 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The molecule/nanodroplet scattering and evaporation of molecules from nanodroplets are determined by equilibrium conditions and the weight and diameters of nanodroplets, but do not depend on the kinetic characteristics of attacking molecules. However, the values and directions of velocities of attacking molecules relative to nanodroplet surfaces, as well as orientation of molecules at droplet surfaces, are expected to affect the collision processes, leading to scattering or condensation [54].…”

Section: Figmentioning

confidence: 99%

A study of the evaporation and condensation of n-alkane clusters and nanodroplets using quantum chemical methods

Gun’ko

Nasiri

Sazhin

2014

Fluid Phase Equilibria

View full text Add to dashboard Cite

The evaporation rate () of n-alkane molecules in the C 8 -C 27 range from molecular clusters and nanodroplets is analysed using the quantum chemical solvation model (SMD) and the kinetic gas theory, assuming that the system is in a state of thermodynamic equilibrium (evaporation and condensation rates are equal). The droplet size, liquid density, evaporation enthalpy and Gibbs free energy of evaporation are calculated at 300-640 K. The quantum chemical calculations (SMD/HF or SMD/B3LYP methods with the 6-31G(d,p) basis set) are used to estimate changes in the Gibbs free energy during the transfer of a molecule from a liquid medium (clusters or nanodroplets) into the gas phase. The kinetic gas theory is used to estimate the collision rate of molecules/clusters/nanodroplets in the gas phase. This rate depends on partial pressures, temperature, sizes and masses of molecules and clusters/nanodroplets. An increase in the molecular size of evaporated alkanes from octane to heptacosane results in a strong decrease in the values of . Preliminary estimates of the evaporation/condensation coefficient, based on the direct analysis of the collisions of individual molecules with molecular clusters, are presented.

show abstract

Section: Figmentioning

confidence: 99%

A study of the evaporation and condensation of n-alkane clusters and nanodroplets using quantum chemical methods

Gun’ko

Nasiri

Sazhin

2014

Fluid Phase Equilibria

View full text Add to dashboard Cite

show abstract

“…1,5,6 Although rotator phases have been studied in bulk crystals of alkanes, there are few reports of these phases in molecularly thin films. [7][8][9][10][11]16 Solid C32 films grown on SiO 2 surfaces have been found to follow the Stranski-Krastanov growth mode. At the substrate-alkane interface, there is a complete bilayer of molecules with their long axis parallel to the surface.…”

Section: Introductionmentioning

confidence: 98%

Crystalline-to-plastic phase transitions in molecularly thin n-dotriacontane films adsorbed on solid surfaces

Cisternas

Corrales

Campo

et al. 2009

The Journal of Chemical Physics

View full text Add to dashboard Cite

Crystalline-to-rotator phase transitions have been widely studied in bulk hydrocarbons, in particular in normal alkanes. But few studies of these transitions deal with molecularly thin films of pure n-alkanes on solid substrates. In this work, we were able to grow dotriacontane ͑n-C 32 H 66 ͒ films without coexisting bulk particles, which allows us to isolate the contribution to the ellipsometric signal from a monolayer of molecules oriented with their long axis perpendicular to the SiO 2 surface. For these submonolayer films, we found a step in the ellipsometer signal at ϳ331 K, which we identify with a solid-solid phase transition. At higher coverages, we observed additional steps in the ellipsometric signal that we identify with a solid-solid phase transition in multilayer islands ͑ϳ333 K͒ and with the transition to the rotator phase in bulk crystallites ͑ϳ337 K͒, respectively. After considering three alternative explanations, we propose that the step upward in the ellipsometric signal observed at ϳ331 K on heating the submonolayer film is the signature of a transition from a perpendicular monolayer phase to a denser phase in which the alkane chains contain on average one to two gauche defects per molecule.

show abstract

“…There have been many studies on the structures of the hydrocarbon molecular film prepared by physical vapor deposition methods, such as vacuum evaporation. [3][4][5][6][7] In an evaporated film system with a long chain of hydrocarbon molecules, two typically preferred molecular orientation states were observed. One is the ''perpendicular orientation state,'' in which molecules appear with their chain axes approximately perpendicular to the substrate surface, and the other is the ''parallel orientation state,'' in which molecular chain axes are parallel to the substrate surface.…”

mentioning

confidence: 99%

“…One is the ''perpendicular orientation state,'' in which molecules appear with their chain axes approximately perpendicular to the substrate surface, and the other is the ''parallel orientation state,'' in which molecular chain axes are parallel to the substrate surface. [3][4][5][6][7] Molecular orientation behavior depends on preparation conditions. In a fatty acid 3 and n-alkane evaporated films, 7 the perpendicular orientation state tends to appear when the deposition rate is low or the substrate temperature is high.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Structures of Multilayered Thin Films of Long-Chain Molecules: X-ray Scattering Study

Tanaka

Ishikawa

Nozaki

et al. 2008

Polym J

Self Cite

View full text Add to dashboard Cite

The structures of the multilayered thin films of hydrocarbon molecules, which are n-C 23 H 48 (C23), n-C 25 H 52 (C25), and n-ClC 20 H 40 Cl (C20Cl), have been investigated by means of X-ray diffraction. The alternatively layered thin films of two hydrocarbon molecules, the C23/C25/C23/C25/Si, C23/C25/Si, C25/C20Cl/Si, and C20Cl/C25/Si films, were prepared by vacuum evaporation on the Si substrate. The multilayered structural parameters, which are the chain length in each layer, the number of molecule in a layer, the layer thickness, the total film thickness, and the interface structure between different layers are determined from X-ray scattering profiles by using the multilayered model. The obtained parameters are considered to agree with those determined by other techniques. It is concluded that the interface between the different layers of the multilayered films except the C25/C20Cl/Si film are smooth. While in the case of the C25/C20Cl/Si film, the interface structure is disordered. The different deposition sequence leads to difference in interface structure.

show abstract

Structure of Normal Alkane Evaporated Films: Molecular Orientation

Cited by 16 publications

References 36 publications

A study of the evaporation and condensation of n-alkane clusters and nanodroplets using quantum chemical methods

A study of the evaporation and condensation of n-alkane clusters and nanodroplets using quantum chemical methods

Crystalline-to-plastic phase transitions in molecularly thin n-dotriacontane films adsorbed on solid surfaces

Structures of Multilayered Thin Films of Long-Chain Molecules: X-ray Scattering Study

Contact Info

Product

Resources

About