Growth of two-dimensional rhenium disulfide (ReS2) nanosheets with a few layers at low temperature

CrystEngComm ◽  
2017 ◽  
Vol 19 (36) ◽  
pp. 5341-5345 ◽  
Author(s):  
Saeah Kim ◽  
Hak Ki Yu ◽  
Seokhyun Yoon ◽  
Nam-Suk Lee ◽  
Myung Hwa Kim
Keyword(s):  
Low Temperature ◽  
Gas Phase ◽  
Ambient Pressure ◽  
Reaction Process ◽  
Phase Reaction ◽  
Two Dimensional ◽  
Single Crystalline ◽  
Gas Phase Reaction ◽  
Si Wafer

Single-crystalline ReS2 nanosheets with a few layers were vertically grown on a SiO2/Si wafer by a gas phase reaction process at ambient pressure.

Low Temperature Si Homoepitaxy by a Reactive CVD with a SiH4/F2 Mixture

2009 ◽  
Vol 1153 ◽  
Author(s):  
Akihisa Minowa ◽  
Michio Kondo
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Substrate Temperature ◽  
Gas Phase ◽  
Deposition Rate ◽  
Flow Rate ◽  
Exothermic Reaction ◽  
Phase Reaction ◽  
Single Crystalline ◽  
Gas Phase Reaction

AbstractSingle crystalline Si thin films on insulating substrates (SOI) have a variety of potential applications to such as high mobility TFT and to high efficiency and low cost solar cells. Since the SOI is limited to a thin layer, it is needed to develop a low temperature epitaxial growth technology to form active layers thicker than several micorns at low temperatures. The purpose of this study is to develop a deposition technique of single crystalline Si thin films by a reactive CVD method [1] at temperatures less than 600○C utilizing gas-phase reaction (SiH4, F2). Deposition of Si films was performed on a single crystalline Si (100) wafer. Substrate-temperature was varied between 100 and 700○C, reaction-pressure 1 and 500mTorr, flow-rate between SiH4/F2 = 1/1 and 1/3, and the geometry of the substrate and the gas-outlet were optimized. First, it was found that deposition rate was sensitive to the distance between the gas-outlet and the substrate and to the total pressure. For four different combinations of pressures, 250 and 500 mTorr and distances, 50 and 150 mm. The deposition took place only for the combination of 500 mTorr and 50 mm, and otherwise the deposition rate was significantly lower or etching of Si wafer was observed. The deposition rate for gas flow ratio, SiH4/F2 of 1/1 was 1.7 nm/s at a substrate-temperature of 400○C, while for higher F2 flow rate ratio, SiH4/F2 = 1/2 and 1/3, the deposition rates were 8.3×10-3 nm/s and etching, respectively. Raman measurements show that crystallinity depends on the substrate-temperature; broad amorphous signal appears at 300, microcrystalline signal at 300 and 500○C and sharp crystalline at 400○C. RHEED observation shows a halo-pattern of amorphous-Si at 200○C, a mixed pattern of streak and spot without 2×1 superstructure at 300○C, a 2×1 streak-pattern at 400○C and a spot-pattern at 500○C. The reason of the narrow temperature window for epitaxial layer is a characteristic feature of low temperature epitaxy as reported before [2]. It is noteworthy the deposition rate of epitaxy obtained in this work is quite high, 1.7 nm/s even at 400○C. These observations are ascribed to the gas phase reaction between SiH4 and F2 and successive surface reactions. The SiH4 and F2 cause an exothermic reaction in the gaseous phases to generate radicals such as SiHx, H and F. The SiHx acts as a film precursor and others act as etchant. Under the conditions which radical density ratio SiHx/F increases, therefore, the deposition rate decreases or etching occurs. The material properties also will be discussed in relation to the growth mechanism. [1]J. Hanna et al., J. Non-Crst. Solids 114 (1989) 172-174 [2]T. Kitagawa, M. Kondo et al, Appl. Surf. Sci. 159-160 (2000) 30-34

scholarly journals Pressure dependent low temperature kinetics for CN + CH3CN: competition between chemical reaction and van der Waals complex formation

2016 ◽  
Vol 18 (22) ◽  
pp. 15118-15132 ◽  
Author(s):  
Chantal Sleiman ◽  
Sergio González ◽  
Stephen J. Klippenstein ◽  
Dahbia Talbi ◽  
Gisèle El Dib ◽  
...  
Keyword(s):  
Low Temperature ◽  
Complex Formation ◽  
Gas Phase ◽  
Rate Coefficient ◽  
Flow Reactor ◽  
Slow Flow ◽  
Phase Reaction ◽  
Gas Phase Reaction ◽  
Low Temperature Kinetics ◽  
Temperature And Pressure

The gas phase reaction between the CN radical and acetonitrile CH3CN was investigated experimentally with a CRESU apparatus and a slow flow reactor as well as theoretically to explore the temperature and pressure dependence of its rate coefficient from 354 K down to 23 K.

Gas-Phase Reaction of NOXFormation in Oxyfuel Coal Combustion at Low Temperature

2011 ◽  
Vol 25 (6) ◽  
pp. 2481-2486 ◽  
Author(s):  
Ryo Yoshiie ◽  
Takuya Kawamoto ◽  
Daisuke Hasegawa ◽  
Yasuaki Ueki ◽  
Ichiro Naruse
Keyword(s):  
Low Temperature ◽  
Gas Phase ◽  
Coal Combustion ◽  
Phase Reaction ◽  
Gas Phase Reaction

scholarly journals A low temperature investigation of the gas-phase N(2D) + NO reaction. Towards a viable source of N(2D) atoms for kinetic studies in astrochemistry

2018 ◽  
Vol 20 (25) ◽  
pp. 17442-17447 ◽  
Author(s):  
Dianailys Nuñez-Reyes ◽  
Kevin M. Hickson
Keyword(s):  
Nitric Oxide ◽  
Supersonic Flow ◽  
Low Temperature ◽  
Gas Phase ◽  
Flow Reactor ◽  
Kinetic Studies ◽  
Phase Reaction ◽  
Atomic Nitrogen ◽  
Gas Phase Reaction ◽  
Temperature Range

The gas-phase reaction of metastable atomic nitrogen N(2D) with nitric oxide has been investigated over the 296–50 K temperature range using a supersonic flow reactor.

Detachment of CVD-grown graphene from single crystalline Ni films by a pure gas phase reaction

2016 ◽  
Vol 653 ◽  
pp. 143-152 ◽  
Author(s):  
Patrick Zeller ◽  
Ann-Kathrin Henß ◽  
Michael Weinl ◽  
Leo Diehl ◽  
Daniel Keefer ◽  
...  
Keyword(s):  
Gas Phase ◽  
Phase Reaction ◽  
Single Crystalline ◽  
Gas Phase Reaction ◽  
Grown Graphene

Gas-phase reactivity of CH3C(O) CH3 with OH radicals at interstellar Temperatures (T = 11.7 – 64.4 K) using the CRESU technique

2019 ◽  
Vol 15 (S350) ◽  
pp. 379-381
Author(s):  
Sergio Blázquez ◽  
Antonio J. Ocaña ◽  
Alberto García ◽  
Bernabé Ballesteros ◽  
André Canosa ◽  
...  
Keyword(s):  
Supersonic Flow ◽  
Low Temperature ◽  
Gas Phase ◽  
Pressure Dependence ◽  
Freezing Point ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Gas Condensation ◽  
Gas Phase Reaction

AbstractThe rate coefficients, k(T= 11.7 – 64.4 K), for the gas-phase reaction between OH radicals and acetone, CH3C(O) CH3, have been measured using the pulsed CRESU (French acronym for Reaction Kinetics in a Uniform Supersonic Flow) technique, the most suitable one to cool down gases below the freezing point without gas condensation. The experimental k(T) was found to increase as temperature was lowered and is several orders of magnitude higher for low temperature than k(300 K). No pressure dependence of k(20 K) and k(64 K) was observed, while k(50 K) at the largest gas density is twice higher than the average values found at lower gas densities. The obtained values of k(11.7 K) and k(21.1 K) were 2.45’10-10 and 1.39’10-10 cm3 molecule-1 s-1, respectively.

scholarly journals Formation of secondary organic aerosol and oligomers from the ozonolysis of enol ethers

2006 ◽  
Vol 6 (12) ◽  
pp. 5009-5024 ◽  
Author(s):  
A. Sadezky ◽  
P. Chaimbault ◽  
A. Mellouki ◽  
A. Römpp ◽  
R. Winterhalter ◽  
...  
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Ambient Pressure ◽  
Organic Aerosol ◽  
Chemical Compositions ◽  
Phase Reaction ◽  
Enol Ethers ◽  
Gas Phase Reaction ◽  
Esi Ms ◽  
Criegee Intermediates

Abstract. Formation of secondary organic aerosol has been observed in the gas phase ozonolysis of a series of enol ethers, among them several alkyl vinyl ethers (AVE, ROCH=CH2), such as ethyl, propyl, n-butyl, iso-butyl, t-butyl vinyl ether, and ethyl propenyl ether (EPE, C2H5OCH=CHCH3). The ozonolysis has been studied in a 570 l spherical glass reactor at ambient pressure (730 Torr) and room temperature (296 K). Gas phase reaction products were investigated by in-situ FTIR spectroscopy, and secondary organic aerosol (SOA) formation was monitored by a scanning mobility particle sizer (SMPS). The chemical composition of the formed SOA was analysed by a hybrid mass spectrometer using electrospray ionization (ESI). The main stable gas phase reaction product is the respective alkyl formate ROC(O)H, formed with yields of 60 to 80%, implying that similar yields of the corresponding excited Criegee Intermediates (CI) CH2O2 for the AVE and CH3CHO2 for EPE are generated. Measured SOA yields are between 2 to 4% for all enol ethers. Furthermore, SOA formation is strongly reduced or suppressed by the presence of an excess of formic acid, which acts as an efficient CI scavenger. Chemical analysis of the formed SOA by ESI(+)/MS-TOF allows to identify oligomeric compounds in the mass range 200 to 800 u as its major constituents. Repetitive chain units are identified as CH2O2 (mass 46) for the AVE and C2H4O2 (mass 60) for EPE and thus have the same chemical compositions as the respective major Criegee Intermediates formed during ozonolysis of these ethers. The oligomeric structure and chain unit identity are confirmed by HPLC/ESI(+)/MS-TOF and ESI(+)/MS/MS-TOF experiments, whereby successive and systematic loss of a fragment with mass 46 for the AVE (and mass 60 for EPE) is observed. It is proposed that the oligomer has the following basic structure of an oligoperoxide, -[CH(R)-O-O]n-, where R=H for the AVE and R=CH3 for the EPE. Oligoperoxide formation is thus suggested to be another, so far unknown reaction of stabilized Criegee Intermediates in the gas phase ozonolysis of oxygen-containing alkenes leading to SOA formation.

Prediction of Alkanolamine pKa Values by Combined Molecular Dynamics Free Energy Simulations and ab initio Calculations

2019 ◽  
Author(s):  
Javad Noroozi ◽  
William Smith
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Ab Initio Calculations ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Phase Reaction ◽  
Pka Values ◽  
Gas Phase Reaction ◽  
Reaction Free Energy ◽  
Energy Simulations

We use molecular dynamics free energy simulations in conjunction with quantum chemical calculations of gas phase reaction free energy to predict alkanolamines pka values. <br>

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