Dynamics of unimolecular reactions induced by monochromatic IR radiation: experiment and theory for C n F m H k I ? C n F m H k + I probed with hyperfine-, doppler- and uncertainty-limited time resolution of iodine-atom IR absorption

1995 ◽  
Vol 102 ◽  
pp. 275 ◽  
Author(s):  
Yabai He ◽  
J�rg Pochert ◽  
Martin Quack ◽  
Roland Ranz ◽  
Georg Seyfang
Keyword(s):  
Time Resolution ◽  
Iodine Atom ◽  
Ir Absorption ◽  
Limited Time ◽  
Ir Radiation ◽  
Unimolecular Reactions

scholarly journals Direct picosecond time resolution of unimolecular reactions initiated by local mode excitation

1986 ◽  
Vol 84 (3) ◽  
pp. 1932-1933 ◽  
Author(s):  
N. F. Scherer ◽  
F. E. Doany ◽  
A. H. Zewail ◽  
J. W. Perry
Keyword(s):  
Time Resolution ◽  
Local Mode ◽  
Unimolecular Reactions ◽  
Mode Excitation

scholarly journals Mass-Loss from Late-Type Stars: New Observational Evidence

1983 ◽  
Vol 103 ◽  
pp. 292-292
Author(s):  
P. G. Wannier ◽  
R. Sahai
Keyword(s):  
Mass Loss ◽  
Central Star ◽  
Ir Absorption ◽  
Late Type ◽  
Ir Radiation ◽  
Loss Mechanism ◽  
Continuum Source ◽  
Near Ir ◽  
Molecular Lines ◽  
Circumstellar Shells

Rapid mass-loss is observed in many late-type stars, yet the mass-loss mechanisms operating are not well understood. A survey of molecular emission from circumstellar shells has been carried out using millimeterwave molecular lines and suggests that radiation pressure alone may be inadequate to explain the observed mass-loss, especially in the case of carbon-rich objects which may display rates in excess of 10−5 M⊙/yr. Recent near-IR molecular line observations provide evidence for ejected material at several different velocities along the line-of-sight and may indicate the additional mass-loss mechanism at work. Resonantly scattered IR radiation spatially displaced from the central IR continuum source has now been observed for the first time and sheds new light on the IR absorption-line results, providing information about material within 1016 cm of the central star. These results are discussed along with recent high-resolution millimeterwave observations.

Infrared Vision Using an Uncooled Thermo-Opto-Mechanical Camera: Design, Microfabrication, and Performance

1999 ◽  
Author(s):  
M. Mao ◽  
T. Perazzo ◽  
O. Kwon ◽  
Y. Zhao ◽  
A. Majumdar ◽  
...  
Keyword(s):  
Optical Design ◽  
Thermomechanical Analysis ◽  
Absorption Enhancement ◽  
Geometrical Shape ◽  
Ir Absorption ◽  
Residual Tensile Stress ◽  
Ir Radiation ◽  
Ir Camera ◽  
Optical Readout ◽  
And Performance

Abstract An uncooled infrared (IR) camera that is based on thermomechanical sensing and visible optical readout has been developed. The system contains a focal plane array (FPA) consisting of bimaterial cantilever beams made of silicon nitride (SiNx) and gold (Au) in each pixel. Absorption of incident IR radiation in the 8–14 μm wavelength range by SiNx in each cantilever beam raises its temperature, resulting in proportional deflection due to mismatch in thermal expansion of the two cantilever materials. To maximize the thermal performance, the conductance of each pixel was reduced to about five times of the radiation conductance. Based on thermomechanical analysis, the geometrical shape of the pixels were designed to maximize the cantilever sensitivity within the constraints of the pixel size and layout. Microfabrication of stress-balanced bimaterial cantilevers was achieved by varying the silicon concentration along the thickness of the SiNx films in order to balance the residual tensile stress in the Au film and the Cr adhesion layer between Au and SiNx. The optical design of each pixel was based on IR properties of the cantilever materials, IR absorption enhancement due to resonance cavity formation, as well as visible optics of deformable diffraction gratings. The latter formed the foundation for two different optical readout techniques that were both used for IR imaging. The results suggest that objects at temperatures as low as 30 °C can be imaged with the best noise-equivalent temperature difference (NETD) in the range of 2–5 K. It is estimated that further improvements that are currently being pursued can improve NETD to about 10 mK.

Stochastic modelling of a single ion channel : an alternating renewal approach with application to limited time resolution

1988 ◽  
Vol 233 (1272) ◽  
pp. 247-292 ◽  
Keyword(s):  
Time Resolution ◽  
Markov Models ◽  
Single Channel ◽  
Renewal Theory ◽  
Stochastic Modelling ◽  
Model Parameters ◽  
Limited Time ◽  
Numerical Studies ◽  
Open Time

Stochastic models of ion channels have been based largely on Markov theory where individual states and transition rates must be specified, and sojourn-time densities for each state are constrained to be exponential. This study presents an approach based on random-sum methods and alternating-renewal theory, allowing individual states to be grouped into classes provided the successive sojourn times in a given class are independent and identically distributed. Under these conditions Markov models form a special case. The utility of the approach is illustrated by considering the effects of limited time resolution (modelled by using a discrete detection limit, ξ) on the properties of observable events, with emphasis on the observed open-time (ξ-open-time). The cumulants and Laplace transform for a ξ-open-time are derived for a range of Markov and non-Markov models; several useful approximations to the ξ-open-time density function are presented. Numerical studies show that the effects of limited time resolution can be extreme, and also highlight the relative importance of the various model parameters. The theory could form a basis for future inferential studies in which parameter estima­tion takes account of limited time resolution in single channel records. Appendixes include relevant results concerning random sums and a discussion of the role of exponential distributions in Markov models.

scholarly journals Passive Infrared Sensing Using Plasmonic Resonant Dust Particles

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Mark Mirotznik ◽  
William Beck ◽  
Kimberly Olver ◽  
John Little ◽  
Peter Pa
Keyword(s):  
Design Methodology ◽  
Computational Design ◽  
Experimental Results ◽  
Dust Particles ◽  
Ir Absorption ◽  
Ir Radiation ◽  
Design Algorithm ◽  
Infrared Sensing ◽  
Subwavelength Gratings ◽  
Quarter Wavelength

We present computational and experimental results of dust particles that can be tuned to preferentially reflect or emit IR radiation within the 8–14 μm band. The particles consist of thin metallic subwavelength gratings patterned on the surface of a simple quarter wavelength cavity. This design creates distinct IR absorption resonances by combining the plasmonic resonance of the grating with the natural resonance of the cavity. We show that the resonance peaks are easily tuned by varying either the geometry of the grating or the thickness of the cavity. Here, we present a computational design algorithm along with experimental results that validate the design methodology.

Statistical inference from single channel records: two-state Markov model with limited time resolution

1988 ◽  
Vol 235 (1278) ◽  
pp. 63-94 ◽  
Keyword(s):  
Statistical Inference ◽  
Time Resolution ◽  
Single Channel ◽  
Confidence Regions ◽  
Point Estimation ◽  
Limited Time ◽  
General Applicability ◽  
Open Time ◽  
Model Control ◽  
Single Exponential

Though stochastic models are widely used to describe single ion channel behaviour, statistical inference based on them has received little con­sideration. This paper describes techniques of statistical inference, in particular likelihood methods, suitable for Markov models incorporating limited time resolution by means of a discrete detection limit. To simplify the analysis, attention is restricted to two-state models, although the methods have more general applicability. Non-uniqueness of the mean open-time and mean closed-time estimators obtained by moment methods based on single exponential approximations to the apparent open-time and apparent closed-time distributions has been reported. The present study clarifies and extends this previous work by proving that, for such approximations, the likelihood equations as well as the moment equations (usually) have multiple solutions. Such non-uniqueness corresponds to non-identifiability of the statistical model for the apparent quantities. By contrast, higher-order approximations yield theoretically identifiable models. Likelihood-based estimation procedures are developed for both single exponential and bi-exponential approximations. The methods and results are illustrated by numerical examples based on literature and simulated data, with consideration given to empirical distributions and model control, likelihood plots, and point estimation and confidence regions.

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