Molecular Orientation of Monolayers on Liquid Substrates: Optical Model and FT-IR Methods

Fina, Leslie J.; Tung, Y. S.

doi:10.1366/0003702914336255

Cited by 39 publications

(31 citation statements)

References 21 publications

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“…A series of the MO measurements has been performed on the basis of approximation 10. 11,13,18,24,30,31,32,[49][50][51] However, the difference between 3k iso and k max can be essential. For example, the value of 3k iso ) 0.79 characterizes bulk CdAr dispersed in KBr pellets, 49 which is distinct from the value of k max ) 1.04 found for a 11-monolayer LB film of CdAr on glass.…”

Section: Methodsmentioning

confidence: 99%

A New Approach to the IR Spectroscopic Study of Molecular Orientation and Packing in Adsorbed Monolayers. Orientation and Packing of Long-Chain Primary Amines and Alcohols on Quartz

and

Rao

2001

J. Phys. Chem. B

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A new method is suggested for determining the molecular orientation in adsorbed films with uniaxial and biaxial anisotropy from two (s-and p-polarized) IRRAS spectra of the same sample, measured at the optimal angle of incidence. The method is simple, does not use the film thickness, and is internally stable with respect to the uncertainty in the input optical parameters of the anisotropic film. The advantages and limitations of the method are discussed. To validate the method, we determined the orientation of hexadecylamine and hexadecyl alcohol adsorbed on a quartz surface. It is shown that at a concentration above the concentration of 2D precipitation but below the concentration of 3D precipitation, hydrocarbon chains in the adsorbed amine monolayer are well-packed in a monoclinic (biaxial) subcell with a tilt angle of about 30°. Chaotically arranged crystallites of the amine molecules appear at the surface at a concentration higher than the concentration of 3D precipitation. Adsorbed monolayers of the alcohol turn out to have a hexagonal structure, in which the hydrocarbon tails are "flip-flop" positioned and tilted by 25-30°from the surface normal.

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Section: Methodsmentioning

confidence: 99%

A New Approach to the IR Spectroscopic Study of Molecular Orientation and Packing in Adsorbed Monolayers. Orientation and Packing of Long-Chain Primary Amines and Alcohols on Quartz

and

Rao

2001

J. Phys. Chem. B

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“…RA bands may be positive or negative depending on the polarisation of the incident radiation, the proximity of the angle of incidence to the Brewster angle, the direction of the change in dipole moment during the normal mode of vibration [34], and the complex refractive index of the substrate [1,6,[35][36][37]. Negative absorbance bands have been observed by Dluhy and coworkers [1][2][3]5,10] from phospholipid monolayers at the A/W interface.…”

Section: Ra Ft-ir Spectra In the C-h Stretching Regionmentioning

confidence: 99%

Reflection–absorption FT-IR spectroscopy of pentadecanoic acid at the air/water interface

Sinnamon

Dluhy

Barnes

1999

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…[99,101,153], which also contain some misprints. Below, the Hansen formulas are corrected so as to produce results equivalent to those reported elsewhere [100,101,132,244,245].…”

Section: •mentioning

confidence: 99%

Absorption and Reflection of Infrared Radiation by Ultrathin Films

Tolstoy¹,

Чернышова²,

Skryshevsky³

2003

Handbook of Infrared Spectroscopy of Ultrathin Films

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The primary characteristics that one identifies from infrared (IR) spectra of ultrathin films for further analysis are the resonance frequencies, oscillator strengths (extinction coefficients), and damping (bandwidths), related to different kinds of vibrational, translational, and frustrated rotational motion inside the thin-film material [1][2][3][4][5][6][7]. However, the microscopic processes inside or at the surface of a film (motion of atoms and electrons) give rise to the frequency dependence (the dispersion) not only of the extinction coefficient but also of the refractive index of the film. As a result, a real IR spectrum of an ultrathin film is, as a rule, distorted by so-called optical effects. Specifically, the spectrum strongly depends upon the conditions of the measurement, the film thickness, and the optical parameters of the surroundings and substrate impeding extraction of physically meaningful information from the spectrum. Thus after introduction of the nomenclature accepted in optical spectroscopy and a brief discussion of the physical mechanisms responsible for absorption by solids on a qualitative level, this introductory chapter will concentrate on the basic macroscopic or phenomenological theory of the optical response of an ultrathin film immobilized on a surface or at an interface.The theoretical analysis of the IR spectra of ultrathin films on various substrates and at interfaces will involve two assumptions: (1) the problem is linear and (2) the system under investigation is macroscopic; that is, one can use the macroscopic Maxwell formulas containing the local permittivity. The first assumption is valid only for weak fields. The second assumption means that the volume considered for averaging, a (the volume in which the local permittivity is formed), is lower than the parameter of inhomogeneity of the medium, d (e.g., the effective thickness of the film, the size of islands, or an effective dimension of polariton), a < d. In this case, the response of the medium to the external electromagnetic field is essentially the response of a continuum. The 1

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Molecular Orientation of Monolayers on Liquid Substrates: Optical Model and FT-IR Methods

Cited by 39 publications

References 21 publications

A New Approach to the IR Spectroscopic Study of Molecular Orientation and Packing in Adsorbed Monolayers. Orientation and Packing of Long-Chain Primary Amines and Alcohols on Quartz

A New Approach to the IR Spectroscopic Study of Molecular Orientation and Packing in Adsorbed Monolayers. Orientation and Packing of Long-Chain Primary Amines and Alcohols on Quartz

Reflection–absorption FT-IR spectroscopy of pentadecanoic acid at the air/water interface

Absorption and Reflection of Infrared Radiation by Ultrathin Films

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