Nonlinear IR Research Articles

Mechanism of attraction of the lovebug, Plecia nearctica, to southern highways: further evidence for the IR-dielectric waveguide theory of insect olfaction

Irradiated automobile exhaust fumes and their components were tested as an attractant for the lovebug, Plecia nearctica Hardy. Of the five different aldehydes tested, formaldehyde and heptaldehyde were the two most attractive. Formaldehyde is the abundant aldehyde in the fumes of diesel exhaust and is probably the single most important attractant. A generalized description is given of the female antennae. Three different types of sensillum (spine) match the 1-2-wavelength criteria for an open-resonator dielectric antenna, as given by Kiely. A nonlinear IR spectrum obtained by blowing saturated formaldehyde air through a punch-hole scatter antenna is given. The 10.93-, 22.73-, 26.88-, 32.79-, and 42.19-,um maserlike lines match the predicted wavelength resonant modes for the three sensilla. This is considered direct evidence for a man-generated wavelength mimic of a natural attractant and also direct evidence of the validity of Callahan's dielectric waveguide-nonlinear system. molecular (maserlike) emission theory of the insect communication.

Nonlinear ir properties of an LO phonon in thin KReO4films

Nonlinear ir absorption has been measured in an LO phonon in thin KRe${\mathrm{O}}_{4}$ films at room temperature. The excited-state lifetime is at least two orders of magnitude longer than that observed for the corresponding single-ion vibrational mode in matrix-isolated Re${\mathrm{O}}_{4}^{\ensuremath{-}}$. We attribute the long lifetime to the restrictions imposed by phonon momentum conservation within the film.

Application of upconversion detection to pulsed CO_2 lidar

In this paper the application of an upconversion detector to pulsed CO(2) lidar is investigated. In this device a nonlinear IR crystal would be used to convert 10-microm lidar radiation into the visible region for conventional detection with a photomultiplier tube. A pulsed CO(2) lidar can be substantially improved with an upconversion detector configured for rejection of thermal background radiation using a narrowband filter for the up-converted signal or a cold filter front end. The sensitivity of the upconversion detector with the narrowband visible wavelength filter is estimated to be 2 orders of magnitude better than that of the usual direct detection diode. The cold filter can improve upconversion detection to nearly the signal-shot limit. These upconversion detectors are not limited by speckle noise as is a pulsed heterodyne detector.

Nonlinear IR resonance in a biological system

Nonlinear IR resonance in a biological system

Progress in evaluation of human observer visual detection performance using the ROC curve approach

This perspective is focused on amide groups of peptides interacting with water. 2D IR spectroscopy has already enabled structural aspects of the peptide backbone to be determined through its ability to measure the coupling between different amide-I modes. Here we describe why nonlinear IR is emerging as the method of choice to examine the fast components of the water dynamics near peptides and how isotopically edited peptide links can be used to probe the local water at a residue level in proteins. This type of research necessarily involves an intimate mix of theory and experiment. The description of the results is underpinned by relatively well established quantum-statistical theories that describe the important manifestations of peptide vibrational frequency fluctuations.