Increasing energy efficiency and sensitivity with simple sensor platforms.

We outline and review an approach to the construction of conductometric sensors that demonstrate considerably higher sensitivities than traditional metal oxide sensors. Simple sensor platforms do not require film-based technology, operate at room temperature, and can be obtained without the use of time consuming self-assembly processes. A combined nanopore coated micro-porous array is deposited with nanostructure directing acidic metal oxide island sites which vary in their Lewis acidity, decorate the micropores, and control an electron transduction process. The interaction of analytes with these island sites varies in a predictable manner and can be modified through in-situ functionalization of their Lewis acidity. The micropores allow rapid Fickian diffusion of analytes to the active nanostructured island sites whose reversible interaction with the analyte dominates the sensor response. We require only that the island sites be deposited at sufficiently low concentration so as not to interact electronically with each other. Highly accurate repeat placement of the depositions is not required. The nanoporous walls of the microarray act as a phase match for the deposition of a diversity of nanostructures that are selected for deposition from a variety of easily obtained solution-based sources as the forgiving deposition process requires a minimum of energy consumption and time. Comparisons to a variety of metal oxide systems are considered. Observed sensitivities and the sensor system reversibility can be predicted from the recently developing IHSAB model.

Theoretical prediction of the vibrational spectra of group IB trimers.

The molecular structures of the group IB trimers, Cu(3), Ag(3), and Au(3), have been determined by using the semi-empirical diatomics-in-molecules theory. The trimers are found to have C(2v) symmetry with bond angles between 65 degrees and 80 degrees . The trimers are bound with respect to dissociation to the asymptotic limit of an atom plus a diatom. The binding energies per atom for Cu(3), Ag(3), and Au(3) are 1.08, 0.75, and 1.16 eV, respectively. The vibrational frequencies of the trimers have been determined for comparison with experimental results. The vibrational frequencies are characterized by low values for the bending and asymmetric stretch modes. The frequency of the symmetric stretch of the trimer is higher than the stretching frequency of the corresponding diatomic. A detailed comparison of the theoretical results with the previously measured Raman spectra of matrix isolated Ag(3) is presented.

Three-stage birefringent filter tuning smoothly over the visible region: theoretical treatment and experimental design.

The Jones transformation matrix, which describes the arbitrary incidence of polarized light on a thin uniaxial birefringent plate, is determined. With the optic axis presumed to lie in the plane of the plate, digital solutions to the resulting formulas are presented for several different quartz plates to depict the tuning characteristics of a birefringent plate functioning as a single-stage birefringent filter. A simplified model is used to generalize these results to describe a multistage birefringent filter. This theoretical study forms the basis for the design and construction of a three stage, quartz, birefringent filter to be used as the coarse tuning element in a visible cw dye laser. A relatively simple and straightforward procedure for the assembly of the three-stage filter is given. The performance of this newly constructed filter is found to be superior to currently available commercial models, tuning smoothly over the 4400-6600-A wavelength region.