Temperature-dependent infrared spectra of torsional vibrations in acetic acid

2005 ◽  
Vol 229 (2) ◽  
pp. 151-157 ◽  
Author(s):  
Daniel K. Havey ◽  
Karl J. Feierabend ◽  
Joshua C. Black ◽  
Veronica Vaida
Keyword(s):  
Acetic Acid ◽  
Infrared Spectra ◽  
Torsional Vibrations ◽  
Temperature Dependent

scholarly journals Exploration of Free Energy Surface and Thermal Effects on Relative Population and Infrared Spectrum of the Be6B11− Fluxional Cluster

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 112
Author(s):  
Carlos Emiliano Buelna-Garcia ◽  
José Luis Cabellos ◽  
Jesus Manuel Quiroz-Castillo ◽  
Gerardo Martinez-Guajardo ◽  
Cesar Castillo-Quevedo ◽  
...  
Keyword(s):  
Free Energy ◽  
Infrared Spectrum ◽  
Infrared Spectra ◽  
Thermal Effects ◽  
Global Minimum ◽  
Energy Surface ◽  
Weighted Sums ◽  
Free Energy Surface ◽  
Temperature Dependent ◽  
Relative Population

The starting point to understanding cluster properties is the putative global minimum and all the nearby local energy minima; however, locating them is computationally expensive and difficult. The relative populations and spectroscopic properties that are a function of temperature can be approximately computed by employing statistical thermodynamics. Here, we investigate entropy-driven isomers distribution on Be6B11− clusters and the effect of temperature on their infrared spectroscopy and relative populations. We identify the vibration modes possessed by the cluster that significantly contribute to the zero-point energy. A couple of steps are considered for computing the temperature-dependent relative population: First, using a genetic algorithm coupled to density functional theory, we performed an extensive and systematic exploration of the potential/free energy surface of Be6B11− clusters to locate the putative global minimum and elucidate the low-energy structures. Second, the relative populations’ temperature effects are determined by considering the thermodynamic properties and Boltzmann factors. The temperature-dependent relative populations show that the entropies and temperature are essential for determining the global minimum. We compute the temperature-dependent total infrared spectra employing the Boltzmann factor weighted sums of each isomer’s infrared spectrum and find that at finite temperature, the total infrared spectrum is composed of an admixture of infrared spectra that corresponds to the spectra of the lowest-energy structure and its isomers located at higher energies. The methodology and results describe the thermal effects in the relative population and the infrared spectra.

Far Infrared Group Frequencies. V. Oximes and Aldoximes

1973 ◽  
Vol 27 (1) ◽  
pp. 22-26 ◽  
Author(s):  
S. M. Craven ◽  
F. F. Bentley ◽  
D. F. Pensenstadler
Keyword(s):  
Hydrogen Bond ◽  
Infrared Spectra ◽  
Low Frequency ◽  
Far Infrared ◽  
Torsional Vibrations ◽  
Lattice Vibrations ◽  
Dilute Solutions ◽  
Solid Samples ◽  
Bending Modes ◽  
Bond Stretch

The low frequency infrared spectra from 450 to 75 cm−1 of seven oximes and five aldoximes have been recorded for pure samples and for dilute solutions in cyclohexane. An intense characteristic band is present in the solution spectra at 367 ± 10 cm−1. This characteristic band shifts to 275 ± 10 cm−1 in the spectra of the OD compounds. The 367 ± 10 cm−1 and 275 ± 10 cm−1 bands are assigned to OH and OD torsional vibrations. A comparison of the solution spectra with spectra of the solid samples indicated that the OH … N hydrogen bond stretch of oximes and aldoximes occurs in 300 to 200 cm−1 region. Strong bands also are present in 140 to 100 cm−1 region which are due to OH … N bending modes or perhaps lattice vibrations.

Temperature-dependent Raman and infrared spectra of nucleosides. II?Cytidine

2001 ◽  
Vol 32 (9) ◽  
pp. 795-802 ◽  
Author(s):  
S. A. Lee ◽  
J. Li ◽  
A. Anderson ◽  
W. Smith ◽  
R. H. Griffey ◽  
...  
Keyword(s):  
Infrared Spectra ◽  
Temperature Dependent

Environment and Herbicide Effects on Canada Thistle Ecotypes

Weed Science ◽  
1972 ◽  
Vol 20 (2) ◽  
pp. 163-167 ◽  
Author(s):  
James H. Hunter ◽  
Leon W. Smith
Keyword(s):  
Acetic Acid ◽  
Root Development ◽  
Leaf Damage ◽  
Cirsium Arvense ◽  
Temperature Dependent ◽  
Canada Thistle ◽  
Anisic Acid ◽  
Herbicide Effects ◽  
Increasing Temperature ◽  
Dichlorophenoxy Acetic Acid

Root sections of seven Canada thistle(Cirsium arvense(L.) Scop.) ecotypes were grown under 8, 12, 14, and 16-hr photoperiods at 16, 21, and 27 C. Flowering occurred in all ecotypes under a 16-hr photoperiod. At the 14-hr photoperiod five ecotypes flowered; flowering in three of them was temperature-dependent. Shoot and root development and plant height varied with ecotype. Both the root-to-shoot ratios and the number of shoot buds formed on the roots were inversely related to temperature and length of photoperiod. Herbicides tested for their effects on Canada thistle were 4-amino-3,5,6-trichloropicolinic acid (picloram), 3,6-dichloro-o-anisic acid (dicamba), and (2,4-dichlorophenoxy)acetic acid (2,4-D). Control of top growth increased with increasing temperature. Similarly, root control was maximum at 27 C, at which temperature there were few fleshy roots. Picloram, unlike 2,4-D and dicamba, caused little leaf damage but completely destroyed the root system.

Comparative Studies of Thin Layer Chromatographic Systems for the Separation and Identification of Photoalteration Products of Parathion

1973 ◽  
Vol 56 (2) ◽  
pp. 338-340
Author(s):  
Ronald L Joiner ◽  
Karl P Baetcke
Keyword(s):  
Acetic Acid ◽  
Thin Layer ◽  
Petroleum Ether ◽  
Infrared Spectra ◽  
Ethyl Ether ◽  
Comparative Studies ◽  
Glacial Acetic Acid ◽  
Ammonium Hydroxide ◽  
Rf Values

Abstract Twelve thin layer chromatographic systems were compared for the separation of photoalteration products of parathion. Rf values for each component in each system are presented. Infrared spectra confirmed the identity of separated components. The following 4 systems were designated superior and gave excellent separation of the components: petroleum ether-ethyl ether-glacial acetic acid (80+15+5 and 50+45+5), methanol-chloroform-ammonium hydroxide (24+75+3.5), and methanol-chloroform-petroleum ether (10+20+70).

Multilevel analysis of temperature dependent near-infrared spectra

Talanta ◽  
2015 ◽  
Vol 131 ◽  
pp. 170-174 ◽  
Author(s):  
Ruifeng Shan ◽  
Yue Zhao ◽  
Mengli Fan ◽  
Xiuwei Liu ◽  
Wensheng Cai ◽  
...  
Keyword(s):  
Multilevel Analysis ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Temperature Dependent ◽  
Near Infrared Spectra
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