Spectra of Homologous Series of Monosubstituted Amides

Infrared spectra of the pure liquid and of dilute solution were observed for N‐methyl, N‐ethyl, N‐propyl, and N‐butyl acetamides and propionamides and of N‐deuterated N‐butylacetamide. Also infrared spectra of N15‐butylacetamide and N‐deuterated N15‐butylacetamide and the Raman spectra of N‐butylacetamide and N‐deuterated N‐butylacetamide were observed. In each series a band in the higher members was related to each band of the N‐methyl compound on the basis of similarity in frequency, intensity, band width, and the influence of dilution. In N‐methylacetamide and N‐butylacetamide bands thus related were found to have also similar Raman activities and similar shifts on replacing the peptide hydrogen by deuterium. The extra bands could be related systematically to the extra CH2 groups. The implications of these results in protein spectroscopy and in the spectroscopic study of homologous series is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70627/2/JCPSA6-29-5-1097-1.pd

The Out‐of‐Plane Deformation Frequency of the NH Group in the Peptide Link

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70613/2/JCPSA6-21-3-570-2.pd

The Effect of Hydrogen Bonding on the Hindered Rotation of the Hydroxyl Group in Alcohols

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69594/2/JCPSA6-20-12-1977-1.pd

Effect of Hydrogen Bonding on the Deformation Frequencies of the Hydroxyl Group in Alcohols

The effects of hydrogen bonding on the infrared spectra of aliphatic alcohols have been studied in the range 4000 to 350 cm—1. Twenty‐six alcohols were investigated of which 10 were primary, 7 were branched primary, 6 were secondary, and 3 were tertiary. Attention was concentrated on the region of the spectrum between 1500 cm—1 and 350 cm—1 where the deformation vibrations of the OH group occur. Spectra were obtained of the alcohols (a) in dilute solution in nonpolar solvents, (b) in the liquid state, and (c) in the vapor state, the degree of association being followed by observation of the well‐known effect of hydrogen bonding in the OH stretching vibration near 3.0μ. Methanol, ethanol, and hexanol‐1 were also investigated after deuteration of the OH group. All the alcohols exhibited a broad diffuse association band with a maximum near 650 cm—1. This has been assigned to the out‐of‐plane deformation vibration of the H atom in the COH group. All the alcohols also exhibited a broad association band which usually had 2 maxima near 1410 cm—1 and 1330 cm—1. This band (which appears to have been missed by previous workers) is assigned to the in‐plane deformation vibration of the H atom in the COH group. The corresponding monomeric band varies between 1200 cm—1 and 1330 cm—1 in undeuterated alcohols and between 870 cm—1 and 930 cm—1 in deuterated alcohols. There is in addition a very narrow association band which lies near 1100 cm—1 in primary and secondary alcohols and near 1165 cm—1 in tertiary alcohols. This is assigned to the effect of hydrogen bonding on the skeletal vibrations, which involve stretching of the CO bond. It appears that the effects of hydrogen bonding on the deformation motions of the OH group are quite complex and that steric effects, rotational isomerism, and interaction with C ☒ H deformation frequencies may all be involved to some extent.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71317/2/JCPSA6-24-3-559-1.pd

Effect of Intermolecular Interactions between CH Frequencies on the Infrared Spectra of N‐Paraffins and Polythene

A systematic study has been made of the infrared absorption band near 725 cm—1 which arises from the rocking vibration of methylene groups in n‐paraffins and in polyethylene. In unoriented crystals of n‐paraffins, this band exhibits two components of equal intensity below the transition point; above the transition temperature and in the liquid state only the higher frequency component is found. In solid cold‐drawn polyethylene the two components are of unequal intensity, the low frequency component being the stronger; in liquid polyethylene only the lower frequency component is found. Studies were made of polyethylene in various states of crystallinity and orientation, using both polarized and unpolarized radiation. The results obtained can be consistently interpreted, if the higher frequency component is attributed to crystallites in the polyethylene and the lower frequency component is assumed to be due partly to the crystalline and partly to the amorphous form of the polyethylene. It is concluded that the doubling of this frequency arises from some interaction between methylene groups which is peculiar to the crystalline state of long chain n‐paraffins below their transition points.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69988/2/JCPSA6-22-12-1993-1.pd

Universal Level dynamics of Complex Systems

. We study the evolution of the distribution of eigenvalues of a $N\times N$ matrix subject to a random perturbation drawn from (i) a generalized Gaussian ensemble (ii) a non-Gaussian ensemble with a measure variable under the change of basis. It turns out that, in the case (i), a redefinition of the parameter governing the evolution leads to a Fokker-Planck equation similar to the one obtained when the perturbation is taken from a standard Gaussian ensemble (with invariant measure). This equivalence can therefore help us to obtain the correlations for various physically-significant cases modeled by generalized Gaussian ensembles by using the already known correlations for standard Gaussian ensembles. For large $N$-values, our results for both cases (i) and (ii) are similar to those obtained for Wigner-Dyson gas as well as for the perturbation taken from a standard Gaussian ensemble. This seems to suggest the independence of evolution, in thermodynamic limit, from the nature of perturbation involved as well as the initial conditions and therefore universality of dynamics of the eigenvalues of complex systems.Comment: 11 Pages, Latex Fil

Exact calculation of the ground-state dynamical spin correlation function of a S=1/2 antiferromagnetic Heisenberg chain with free spinons

We calculate the exact dynamical magnetic structure factor S(Q,E) in the ground state of a one-dimensional S=1/2 antiferromagnet with gapless free S=1/2 spinon excitations, the Haldane-Shastry model with inverse-square exchange, which is in the same low-energy universality class as Bethe's nearest-neighbor exchange model. Only two-spinon excited states contribute, and S(Q,E) is found to be a very simple integral over these states.Comment: 11 pages, LaTeX, RevTeX 3.0, cond-mat/930903

Thermodynamics of an one-dimensional ideal gas with fractional exclusion statistics

We show that the particles in the Calogero-Sutherland Model obey fractional exclusion statistics as defined by Haldane. We construct anyon number densities and derive the energy distribution function. We show that the partition function factorizes in the form characteristic of an ideal gas. The virial expansion is exactly computable and interestingly it is only the second virial coefficient that encodes the statistics information.Comment: 10pp, REVTE

Vibrational Spectrum of N‐Methyl Formamide

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70491/2/JCPSA6-26-3-716-2.pd