Sarah L Gilbert | PubMed Health

PubMed2004

Multiple-wavelength reference based on interleaved, sampled fiber Bragg gratings and molecular absorption.

We present a wavelength calibration reference based on interleaved, sampled fiber Bragg gratings stabilized to a molecular absorption line. Such a hybrid reference can provide multiple stable calibration peaks over a wide range of wavelengths. We demonstrate a wavelength reference that has at least 20 peaks suitable for use as calibration references in each of three wavelength regions: 850, 1300, and 1550 nm. We monitored the stability of a 1300-nm reflection peak and found that the standard deviation of the peak wavelength was 0.7 pm over a 70-day period.

Journal Article↗

PubMed2004

Amperometric method for determining the degree of complexation of polyelectrolytes with cationic surfactants.

The complexation of sodium polystyrene sulfonate with monovalent cationic surfactants at a microsized liquid/liquid interface has been studied using electrochemistry. The method is based on measurement of surfactant ion transfer across the interface between two immiscible electrolyte solutions (ITIES). The complexation of various cationic surfactants (alkylpyridinium- and trimethylammonium-) with oligosized polystyrene sulfonate was measured. Binding isotherms were used to determine the degree of binding as a function of the surfactant chain length and type of head group. It was found that the hydrophobicity of the surfactant was the predominant factor. The effect of the polyelectrolyte chain length on the binding mechanism was studied using cetylpyridinium chloride as a complexing agent. It was found that binding affinity, as well as cooperativity of the binding process, decreases with decreasing polyelectrolyte chain length. Thermodynamics of surfactant binding was measured using titration microcalorimetry. The thermodynamic data obtained show that the enthalpy of surfactant binding is not dependent on polymer chain length, but an increase in chain length makes the binding process entropically more favorable.

Calorimetry↗

PubMed2002

Interleaved, sampled fiber Bragg gratings for use in hybrid wavelength references.

We discuss the design and fabrication of interleaved, sampled fiber Bragg gratings (ISFBGs) for use in hybrid wavelength calibration references covering the 1300-1600-nm region. We demonstrate use of sampled phase masks (SPMs) to make sampled gratings and ISFBGs. The success of the SPM technique suggests a single-exposure method with an interleaved, sampled phase mask to make ISFBGs.

Journal Article↗