bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Atmospheric Refractive Turbulence on Laser Remote Sensing
Authors: Clifford Steven F.
Published: February 2023

The literature on the effects of refractive turbulence on optical waves is quite extensive.1-3 Until recently few calculations on the effects of turbulence specific to lidar systems have been performed.4,5,6 We will first review the physics of line-of-sight optical propagation through the turbulent atmosphere and then describe the theory as it applies to specific lidar configurations.
Scattering corrections to transmittance measurements of the extinction coefficient of falling snow
Authors: Winchester L. W. , Gimmestad G. G.
Published: February 2023

In order to predict the performance of electro-optical devices in a winter environment, it will be necessary to understand the effects of falling snow on the propagation of visible and infrared radiation. Several groups of investigators1,2 have measured snow transmittance at visible and infrared wavelengths over the past few years, and have attempted to relate the infrared extinction coefficient βir to the visible extinction coefficient βVIS The usual procedure has been to calculate β from the measured transmittance T by using where R is the optical path length. The result of several such investigations 1,2 has been that βir/βvis ≌ 1.4. This result is somewhat surprising, because most snow crystals are quite large compared to either visible or infrared wavelengths, and hence might be expected to cause approximately the same extinction at either wavelength. However, Eq. (1) is not valid if scattered radiation constitutes an appreciable part of the measured transmitted power. Because all optical instruments have a non-zero field of view, scattered radiation can contribute to received power, causing values of β calculated as above to be systematically low. The error will be wavelength dependent, because the angular pattern of scattered radiation is wavelength dependent.
Requirements for Improved Sounding of Atmospheric Temperature Profiles
Authors: Chahine Moustafa T. , Haskins Robert D.
Published: February 2023

We will briefly discuss the concept of a high spectral-resolution (λ/Δλ = 1200) infrared sounder capable of doubling the current vertical resolution of atmospheric temperature profiles and improving their accuracy from ~2.5K to ~1.5K. In addition the improved sounder permits improved determination of a wide variety of meteorological parameters on cloudiness, surface temperature and air-surface interactions. These improvements are accomplished in part through multispectral observations with a set of narrow band-pass channels properly selected from the high J-lines in the R-branch of the 4.3 μm CO2 band. This set is complemented by a larger set of window, humidity and temperature channels in the 3.7, 6.3, 9 and 15 μm regions positioned away from absorption lines due to minor atmospheric constituents. To implement this concept an Advanced Moisture and Temperature Sounder (AMTS) design is currently under study.
Remote Sensing Technique for Measuring Atmospheric Pressure from a Satellite Using a Multicolor Laser Altimeter
Authors: Gardner C. S. , Tsai B. M. , Abshire J. B.
Published: February 2023

A technique for remotely measuring atmospheric pressure was proposed in a previous paper1. The technique is based on the fact that the difference between the optical pathlengths from a satellite to a ground target measured at two wavelengths is proportional to the atmospheric pressure at the target. The major error source is the differential pathlength measurement. The expected measurement accuracy is plotted in Figure 1 versus the satellite elevation angle. For a system operating at the fundamental (1.06 μm) and tripled (0.353 μm) YAG laser frequencies and with the laser pointing at nadir, the RMS pressure error (σp) is given by where σTd is the differential arrival time error. To obtain pressure accuracies at the millibar level, it is necessary to measure the differential arrival time with an accuracy of a few picoseconds or equivalently measure the differential pathlength with an accuracy of a few millimeters. If the ground target is a non-dispersive retroreflector and the laser pulse length is a few centimeters or less, millimeter level accuracy is feasible with current technology2,3. However, for the situation of greatest practical interest, the target is the ocean surface. Since the local surface height of the ocean can vary over a range of a few meters, the reflected pulse may be broadened to a few meters in length4. The problem is further complicated by the fact that the surface profile within the laser footprint is random and it is impossible to predict the mean return pulse shape in advance. As a consequence, it will be necessary to use less accurate suboptimal signal processing strategies to compute the differential pulse delay from the received signals.
Remote Sensing of Trace Gases with Tunable Diode Lasers
Authors: Reid J. , Cassidy D.T.
Published: February 2023

Tunable diode lasers (TDLs) are often used in point monitoring instruments for the detection of atmospheric trace gases and pollutants. For this application the gas sample flows through a multipass cell at a reduced pressure (~30 Torr), and the resulting narrow infrared absorption lines are detected with very high sensitivity. Several problems must be overcome before similar sensitivities are attained in remote sensing applications under atmospheric conditions. One must contend with broader absorption lines, overlapping and interference from other molecular species, and the presence of atmospheric turbulence. An important system constraint on remote sensing with TDLs is imposed by the low output powers of the TDLs (typically < 1 mW). A cooperative target such as a retroreflector must be employed at the remote site to define the measurement volume. However, if such a target is available, a TDL-based sensing system is extremely versatile and has the potential for higher sensitivity than other infrared remote sensing technologies.
Differential Absorption Lidar Measurements of Atmospheric Species
Authors: Browell Edward V.
Published: February 2023

Interest in remote measurements of atmospheric gases has gained increased emphasis in recent years because of the need to assess the impact of man's activity on his environment. It has been recognized that knowledge of the sources, sinks, transport, and chemistry of atmospheric species must be obtained over large scales to understand the balance between natural and anthropogenic processes. An example of this is the debate over the relative importance of transport of O3 from the stratosphere into the troposphere compared to the production of O3 in the troposphere resulting from anthropogenic activity. This type of investigation requires the use of advanced remote sensing technology. The Differential Absorption Lidar (DIAL) technique is the most versatile of the remote sensing techniques for the measurement of gas concentration profiles with high spatial resolution at ranges of several kilometers or more.
Coherent Doppler Lidars for Wind Sensing in the Atmosphere
Authors: Hall Freeman F.
Published: February 2023

The development of wind sensing coherent Doppler lidars over the past 15 years has progressed from CW homodyne to sophisticated, pulsed heterodyne systems.
Comparison of Heterodyne and Direct Detection CO2 Dial Measurements*
Authors: Killinger D. K. , Menyuk N. , DeFeo W. E.
Published: February 2023

A dual-CO2 laser differential-absorption LIDAR (DIAL) system has been developed which incorporates both direct-detection and heterodyne-detection of the same LIDAR returns. This system has been used to compare experimentally the signal-to-noise ratios and statistical properties of the DIAL returns. A description of the experimental system and some preliminary data were presented previously.1 This paper presents additional data in the context of their application for the laser remote sensing of atmospheric species. Specifically, a comparison is made between the two detection techniques in terms of the increased signal strength accompanied with increased fluctuations of the heterodyne system and the increased accuracy but shorter detection range capability of the direct-detection system.
Stratospheric HCl and HF Measurements
Authors: Mankin William G. , Coffey M. T.
Published: February 2023

One of the major chemical cycles controlling the concentration of ozone in the stratosphere is the catalytic destruction of ozone by chlorine1. The principal source of free chlorine in the stratosphere is believed to be the photolysis of chlorofluoromethanes (CFMs) released in the troposphere by human activity. The principal sink of stratospheric chlorine is HCl, which diffuses downward to the troposphere where it rains out. HCl also serves as a temporary reservoir for chlorine, from which the active Cl can be released by reaction with hydroxyl. The concentration of stratospheric HCl and its variation with height, latitude, and season is thus a key quantity for understanding atmospheric chemistry.
Correlation of Infrared Spectrometric Earth/Atmosphere Data
Authors: Murphy R.E.
Published: February 2023

This paper presents the cross-correlations of infrared data obtained with a mosaic Michelson interferometer while balloon-borne at a float altitude of approximately 30 Km. The interferometer was packaged with a 4x4 mosaic focal plane to provide contiguous ground coverage over a 3.5x3.5 Km area. The cross-correlation statistics, reported here, are useful in regard to remote sensing offering insight into the earth/atmosphere behavior in various spectral bands.
Remote Sensing of Pesticides and Other Contaminant Molecules Using Ultraviolet Lasers and Atomic Resonant Filter Detectors
Authors: Keeler R. Norris , Murarka Narayan , Buhay Harry , Mueller David
Published: February 2023

Using excimer lasers and ultrasensitive detectors it is now possible to remotely detect parts per million of many of the toxic insecticides currently in use in the field today.
A Microwave Tunable Laser Source for Remote Sensing Applications
Authors: Sachse Glen W. , Cheo Peter K.
Published: February 2023

Passive heterodyne radiometry has been demonstrated to be a sensitive, high resolution technique for atmospheric sensing.1,2,3 CO2 LIDAR offers the potential for high vertical resolution measurements of trace gases.4 A Microwave Tunable Laser Source (MTLS) is described that exhibits attractive features for application as a heterodyne local oscillator and for injection locking of high pressure CO2 lasers. The MTLS utilizes a wideband electro-optic modulator to generate tunable optical sidebands (SB) on a CO2 laser carrier. Laser line selection and SB tuning allow precision, piecewise continuous tunability over an inportant atmospheric window (9 to 12 μm) with wavelength accuracy and stability limited only by the CO2 laser.
Differential Absorption Lidar Measurements of the Pressure Profile with a Trough Technique
Authors: Korb C. Laurence , Weng Chi Y.
Published: February 2023

Pressure is one of the basic atmospheric state variables and a knowledge of the pressure-height distribution (pressure profile) is needed in virtually all forecasting systems. This paper describes recent developments for the remote measurement of the atmospheric pressure profile and surface pressure. A high resolution differential absorption lidar technique utilizing measurements in the wings of lines in the oxygen A band where the absorption is highly pressure sensitive was first described by Korb.1 This work was later extended to include the use of trough positions, the region of minimum absorption between two strongly absorbing lines.2 Recently, horizontal path atmospheric measurements3 utilizing this technique have been reported with noise levels less than 1 mb. This paper discusses the basic theory of the pressure technique and presents results for the effects of finite bandwidth, shifts in trough position with altitude, and temperature errors. It also compares the accuracy for satellite-based experiments using various trough positions.
Laser Bandwidth and Frequency Stability Effects on Remote Sensing of Atmospheric Pressure as Applied to A Horizontal Path Measurement
Authors: Kalshoven James E. , Walden Harvey
Published: February 2023

The need for a remote sensing system based in space to measure atmospheric pressure at the Earth’s surface provided the stimulus for the concept of monitoring laser energy attenuation in the wing of a molecular resonant absorption line,1 a quantity dependent on ambient pressure. Experimental verification of the technique, using a ground-based, narrow band (less than 0.001 cm-1) CW tunable dye laser system monitoring lines in the oxygen “A” band, has recently been presented.2 However, a pulsed system would normally be used in an operational system because of power requirements, with resulting bandwidth and frequency stability questions that do not arise in a CW system. This paper develops the theory to show the magnitude of these effects and demonstrates its application to oxygen lines selected as optimal for a horizontal path system.
Some CO2 DIAL system considerations
Authors: Rye Barry J.
Published: February 2023

Differential absorption techniques/1/ exploit the lidar equation dependence on atmospheric absorption to infer the concentration of molecular species. This equation has the form where P is received power, A the antenna area, β a backscatter coefficient T the attenuation and E the transmitted energy, all at wavelengths and range characterised by the subscripts λ and r.
Effects of Differential Reflectivity, Background Interference, and Signal Fluctuations on IR Dial Measurement Accuracy*
Authors: Menyuk N. , Killinger D. K.
Published: February 2023

The differential-absorption LIDAR (DIAL) technique is frequently used for the long-range remote sensing of molecular constituents in the atmosphere. This technique usually involves the measurement of the backscattered radiation at two distinct frequencies, v and v′; the two frequencies are chosen such that they correspond to high- and low-absorption frequencies of the molecular species being measured. The concentration of a species in the atmosphere is deduced from the relative changes in the received backscattered LIDAR radiation as the laser frequency is changed between v and v′. The accuracy in the determination of the concentration of the species is affected by several factors. This paper will explore some of these factors and their influence on the accuracy of DIAL measurements.
Heterodyne Spectroscopy
Authors: Allario F. , Hudson Robert D.
Published: February 2023

Principles of laser heterodyne measurements will be reviewed, and spectroscopic requirements for measuring stratospheric molecules from balloon and spacecraft altitudes will be presented for the infrared, sub-mm and mm regions of the spectrum.
Line Widths and Shapes
Authors: Clough S.
Published: February 2023

Theory of line shape will be discussed with emphasis on the relationship between observables and molecular parameters, including consideration of theoretical constraints.
Quenching of Fluorescence of Small Molecules
Authors: McIlrath Thomas J.
Published: February 2023

The technique of fluorescence lidar involves detection of resonance fluorescence, and interpreting the intensity of the fluorescence signal in terms of the number of molecules being excited. A quantitative interpretation of the signal necessarily requires knowledge of the fluorescence quantum yield of the excited molecules at the ambient pressure. At stratospheric or tropospheric pressures the fluorescent yield is inversely proportional to the quenching rate for most species so that an accurate determination of species concentrations is dependent on a similarly accurate determination of the quenching rates. This is in contrast to Raman lidar where the re-emission is prompt and quenching does not play a significant role.
Recent Progress in High-resolution Atmospheric and Laboratory-based Spectroscopic Measurements
Authors: Kendall D.J.W. , Buijs H.L. , Vail G.L. , Bérubé J.N.
Published: February 2023

Since 1975, Bomem Inc. has developed a series of interferometric spectrophotometers for use on aircraft and balloon-borne platforms featuring high-resolution, dynamic alignment and real-time hard-wired numerical filtering. These instruments have been used by several groups to obtain spectroscopic observations of the atmosphere utilizing both solar absorption and emission techniques.
Aerosol Sources of Some Types of Glacier Hydrocarbons
Authors: Wilson H.W. , Scuderi R.
Published: February 2023

Recent analyses of ice and snow have shown that there are traces of hydrocarbons in many glaciers in the North Cascade mountains of Washington. (Scuderi, 1980). The organic compounds collect slowly throughout the year on topical snow, but they reach their maximal concentrations of about 200-500 ng liter-1 on late summer ablation surfaces. In fresh winter snow, however, their concentrations fall well below 100 ng liter-1. Snowfields adjacent to vegetated areas are often abnormally rich in hydrocarbons, typically 3-5 mg liter-1, probably as as a result of the accumulation of plant vapors and debris. Films that collect on the surfaces during the summer are buried by winter snows and become permanent stratigraphic features in the glaciers.
Resolution of the O3/H2O Interference Problem in Detecting Natural Tropospheric OH Via Laser Induced Fluorescence
Authors: Davis D.D. , Rodgers M.O. , Fischer S.D. , Asai K.
Published: February 2023

The OH free radical has now been shown to be of pivotal importance to our understanding of tropospheric photochemistry. The laser induced fluorescence (LIF) technique has been shown to be a highly sensitive method for measuring atmospheric OH in the parts-per-quadrillion to parts-per-trillion concentration range. The high sensitivity of the LIF method, however, can be compromised by the presence of an OH interference signal resulting from the laser photolysis of in-situ O3, i.e.: followed by the very fast reaction (2), Reaction (2), in turn, is in competition with the very efficient quenching process (3).
Atmospheric Temperature Determination from High Resolution Laser Absorption Measurements
Authors: Korb C. Laurence , Kalshoven James E. , Schwemmer Geary K. , Dombrowski Mark
Published: February 2023

Remote measurements of atmospheric temperature have been demonstrated using a high resolution two-frequency laser technique. In addition, a new technique for measuring the temperature dependence of collision broadened line widths is described. Temperature is one of the most important atmospheric state variables needed for weather forecasting and modeling. Remote measurements of temperature with current satellite passive sensors is limited to accuracies of the order of 2.5K with vertical resolution on the order of 5-10 km. This limits the applicability of this data, particularly m the lower atmosphere. Simulations have shown that the use of high resolution pulsed lasers in a range resolved mode (LIDAR) could lead to significant improvements in both accuracy, 1K, and vertical resolution, 2 km, respectively.(1)
Recent Atmospheric Ozone Measurements Related to New Infrared Spectral Data
Authors: Girard A. , Bouchardy A.M. , Flaud J.M. , Camy-Peyret C. , Secroun C. , Barbe A. , Jouve P.
Published: February 2023

IntercomParison of ozone measurements obtained by independent absolute calibration techniques is a major concern for a synoptic ozone survey network.
The Ammonia Infrared Absorption Reinvestigated in Connection with the Voyager Mission to Jupiter and Saturn
Authors: Husson N. , Chedin A. , Scott N.A.
Published: February 2023

The scientific objectives of the IRIS experiment of the Voyager 1 and 2 missions[1] (encounters with Jupiter in March and July 1979) are the study of the atmospheres of Jupiter, Saturn and possibly Uranus, from radiometric measurements in the infrared by means of a Michelson interferometer. For the first time, more than 50000 spectra of Jupiter were recorded with a spectral resolution of 4.3 cm-1.
High Temperature Absorption Spectrum of 4.3 Micron CO2†
Authors: Esplin Mark P. , Sakai Hajime
Published: February 2023

The importance of CO2 as an atmospheric molecule makes the obtaining of high precision band parameters for a great number of bands a significant contribution to both theoretical and experimental studies of our atmosphere. Very accurate parameters on the (00011-00001) band of 12C16O2 have been obtained by Pine and Guelachvili. Their measurment was accomplished by combining two spectra, a room temperature Fourier transform spectrum, and a high temperature tunable laser spectrum.1 There have been numerous measurements of other bands of CO2,2,3 but they were made either with lower resolution spectrometers, or near room temperature where fewer rotational lines were excited, resulting in a less accurate determination of band parameters. In this work a high resolution Michelson interferometer was coupled with a high temperature absorption cell4 heated to 800 K to obtain a high resolution (0.007 cm−1), high temperature spectrum of CO2 in the 4.3 micron region.
Absorption Cross-Section of Ozone as Function of Temperature
Authors: Bass Arnold M. , Paur Richard J.
Published: February 2023

Observations of ozone concentrations in the earth's upper atmosphere are made by using surface-based Dobson spectrophotometers or instruments carried by balloons and orbiting satellites. Analysis of data from these observations requires knowledge of the absorption cross-sections of ozone for the wavelength at which the measurements are made, and for the temperature of the medium in which the ozone is observed. Discrepencies that have been reported among results from these different experiments have called into question the accuracy of the previously reported1 cross-section values.
Line Parameters of Methane from 2400 to 3200 cm−1
Authors: Brown Linda R. , Toth Robert A. , Hunt Robert H. , Brault James W.
Published: February 2023

A comprehensive list of line parameters of methane have beem compiled in the 2400 to 3200 cm−1 region. Experimental positions and line strengths greater than 3×10−5 cm−2 atm−1 using spectra of 0.01 to 0.02 cm−1 resolution. The data were recorded at Florida State University with a 4-passed grating spectrometer and at the Kitt Peak National Observatory using a Fourier Transform Spectrometer. The spectra were taken with the gas sample at room (298±2K) and cold (down to 160K) temperatures using optical densities that ranged from 0.01 to 150 M-Torr. From these data positions (of single lines not overlapped by other absorptions) were measured to ± 0.0001 cm−1 and line strengths to 5% or better. The positions and strengths of blended lines were less accurately determined. Experimental lower state energies were determined for many of the lines in the 2700 to 3200 cm−1 region using the cold data. These were used extensively to determine the quantum assignments of the observed lines.
Spectrum of 13 CO 2 at 3420-3680 cm−1 (2.8 μm)
Authors: Rinsland Curtis P. , Baldacci Agostino , Smith Mary Ann H. , Rao K. Narahari
Published: February 2023

The 2.8 μm region is useful for the sounding of atmosphere pressure since it contains a number of weak and strong CO2 lines allowing a range of altitudes be sensed (1). This region has been selected for the measurement of pressure in the Halogen Occultation Experiment (HALOE, 2). To aid in the identification of spectral lines within this bandpass, we have recorded the absorption spectrum of 13CO2 in the laboratory. The data were obtained in the spectral interval 3420 to 3680 cm−1 with a vacuum grating spectrometer equipped with a 40 cm × 20 cm Harrison-ruled echelle and a 13C-enriched sample of carbon dioxide. The spectra were recorded both at room temperature and at 160°C. In the high temperature data, it was possible to observe transitions from high rotational levels and moderately high vibrational states. Measurements in this single spectral region provided information on 29 vibrational levels, 4 of which have been studied for the first time. Twenty-one bands have been identified, and about 80 percent of the 2000 lines recorded have been given assignments. The spectral resolution was about 0.03 cm−1.
High Resolution Photoelectric VUV Cross Section Measurements of Atmospheric Molecules
Authors: Yoshino K. , Freeman D.E. , Parkinson W.H.
Published: February 2023

Accurate cross sections of the Schumann-Runge (S-R) bands of O2 are needed to determine the opacity of the atmosphere to solar radiation that causes the dissociation of stratospheric constituents such as NO. In particular, the principal photodissociation processes for NO occur in the δ(0,0) and δ(1,0) bands near 191 and 183 nm, respectively; the former is in the range of the S-R (5,0) band, and the latter is in the range of the S-R (9,0) and (10,0) bands. Detailed cross section measurements that resolve the rotational structure of these bands are necessary for the calculation of predissociation rates. However, the determination of accurate cross sections is straight-forward only if the instrumental band width is small compared with the line width being measured. The true cross section of rotationally discrete lines may vary significantly over the instrumental band width, and this can lead to seriously underestimated peak cross sections and distorted line profiles. The two experimental conditions required for cross section measurements of high accuracy for such molecules are the attainment of the highest possible spectroscopic resolution and the use of photoelectric rather than photographic detection.
A 400-MHz Bandwidth Autocorrelation Spectrum Analyzer
Authors: Ekstrom P. A.
Published: February 2023

Autocorrelation spectral analysis has demonstrated excellent stability, flexibility, and noise floor levels in radio astronomy applications, largely due to its predominantly digital signal processing. Extending this approach to the wide bandwidths required in millimeter-wave stratospheric remote sensing requires advances in fast digital signal processing techniques. To reach a target bandwidth of 400 MHz requires an 800-MHz digitizer sample rate and processing throughput. We have produced in quantity the required delay-multiply-count digital building block (or node) operable above 400 MHz We have demonstrated logic of the speed required for the 800-MHz digitizer and the distributor which divides the data into multiple slower streams for processing by the node cascades, but have not yet completed these faster portions. The completed instrument will offer 2% spectral resolution to 400 MHz total instantaneous bandwidth, and 1% resolution for all total bandwidths below 200 MHz. Observation time penalty due to the 3-level signal representation used is 57%.
Analysis of Infrared Laser Atmospheric Transmission Data Base†
Authors: Dowling James A.
Published: February 2023

An extensive data base comprised of atmospheric transmission and associated meteorological measurements has been collected by NRL during the past five years. Long-path extinction measurements at discreet laser frequencies have been supplemented by high resolution FTS data in several recent experiments. The most comprehensive experiment of this nature was performed in 1977 at the Cape Canaveral Air Force Station (CCAFS), Florida using a 5.08 kilometer overwater path. A compendium1 of data from this experiment has been published but until recently only limited analyses2,3 of these data have been performed. The present paper contains comparisons of both line4 and continuum5-7 molecular absorption models with the 1977 CCAFS measurements together with additional information obtained during more recent work.8-10
Trace Methane Absorption Measurements Using a DF Laser Intracavity Spectrophone
Authors: Leslie D. H. , Trusty G. L.
Published: February 2023

The deuterium-flouride (DF) laser emits in the 3.5 to 4.0 μm atmospheric transmission window. Atmospheric absorbers in the window include isotopic water (HDO), N2O, CH4, and small contributions from both line and continuum H2O absorption. The purpose of our study was to measure trace methane absorption at DF laser frequencies, to compare our results with our predictions using the AFGL line parameters compilation, and to develop sensitive spectrophone measurement techniques.
Whole Band Analysis of Absorption Bands of CO2 and N2O
Authors: Hoke M. L. , Shaw J. H. , Hawkins R. L. , Nordstrom R.
Published: February 2023

The spectrum of CO2 shown in Fig.1 consists of several overlapping bands. Three of these bands have been simultaneously analyzed by the technique of whole band analysis (1) to obtain estimates of parameters which allow the calculation of individual line positions, intensities, and halfwidths as well their associated uncertainties. These parameters can be used to obtain a listing, in AFGL format, of values and uncertainties for line position, intensity, halfwidth and lower state energy. These will be presented.
Optical Elements Needs for Soft X Rays
Authors: Allred David D. , Knight Larry V. , Thorne James M.
Published: February 2023

The wavelengths of soft x rays are approximately 500 times shorter than visible wavelengths. This implication is that smoothness and figure must be much better. In addition, for soft x rays, absorbance of all materials is high, and refraction is too small for successful fabrication of prisms and lenses. Nevertheless, a variety of multilayer diffractors (reflectors) and beam splitters have been fielded to supplement naturally occurring crystal diffractors. The specifications of such optical elements will be discussed for existing and projected applications involving soft x rays.
Non-Lorentzian persistent hole shapes in organic glasses and fractal structures of the hosts
Authors: Uemura Sadao , Nakatsuka Hiroki
Published: February 2023

Recently we observed the persistent holes in some ionic-dye doped organic glasses, and found out that although the persistent hole shapes in a monomeric glass host are close to Lorentzian, those in a long chained polymeric glass host deviate very much from Lorentzian shapes.1,2
Single Atom Experiments
Authors: Walther Herbert
Published: February 2023

Recent experiments with the one-atom maser /1/ have demonstrated that it is possible to study the interaction of single Rydberg atoms with a single quantized mode /2/ of a resonant electromagnetic field in a superconducting cavity. The quality factor is high enough to observe the periodic energy exchange between the atom and the field. The statistical and discrete nature of the photon field leads to new dynamic characteristics such as collapse and revial in the Rabi nutation /3/. Most of the observed effects are purely quantum features /4/.
Single Molecule Spectroscopy : Photon Correlation And Electric Field Effect.
Authors: Orrit M. , Bernard J.
Published: February 2023

The first single molecule detection, by Moerner and colleagues [1] in the system pentacene in p-terphenyl crystal via absorption, has been extremely difficult due to photon noise. In our paper [2], we demonstrated for the first time single molecule lines in fluorescence excitation spectra of the same system. This much simpler method provides a dramatic improvement of the signal/noise ratio. It opened the way for a true single molecule spectroscopy (SMS). Since then, several experiments performed using this technique [3-8] have shown the power and promise of this new spectroscopic method. In this report, we want to apply SMS to obtain detailed information about individual molecules and the differences in some spectroscopic properties due to their local surroundings. We also report on preliminary results on electric field effects on single molecule lines.
Photon Antibunching In The Fluorescence Of A Single Dye Molecule Trapped In A Solid
Authors: Basché Th. , Moerner W. E. , Orrit M. , Talon H.
Published: February 2023

The ability to store single atomic ions in a radio-frequency trap by photon-recoil cooling and detect the emitted fluorescence of the single trapped ions has proven to be a successful way to investigate the fundamental interaction of light and matter and to test our understanding of quantum physics1,2. The extension of these studies to molecules has failed so far, because all molecules - even diatomic species - possess several internal degrees of freedom which prevent laser cooling.
Hole Burning in Dye-Doped Rare Gas Matrices
Authors: Geissinger P. , Haarer D.
Published: February 2023

In order to study dye-matrix interactions in simple model systems, we have incorporated free base phthalocyanine (H2Pc) in solid, rare gas matrices of argon, krypton, and xenon. For the first time, the widths of spectral holes burnt at T≈4K in dye-doped rare gas matrices were determined.
Dephasing and Temperature Cycling in Photochemical Hole-Burning Experiments on Dihydrophenazine in Fluorene Single Crystals
Authors: Prass B. , von Borczyskowski C. , Stehlik D.
Published: February 2023

Dephasing processes observed via hole-burning in dihydrophenazine doped fluorine crystals are discussed in context with an exchange model and the reorientation of dihydrophenazine upon excitation.
Single Molecule Spectroscopy: Polarization Measurements of Pentacene in p-Terphenyl
Authors: Sepiol Jerzy , Güttler Frank , Pirotta Marco , Renn Alois , Wild Urs P.
Published: February 2023

In 1989 Moerner and Kador succeeded in detecting single molecules in absorption with a sophisticated double modulation technique [1]. A much better signal to background ratio was obtained by Orrit and Bernard [2] using the method of fluorescence excitation. Single molecule spectroscopy allows to study the distribution of molecular properties and not only the statistical average which is generally observed. Wild, Güttler, Pirotta and Renn have investigated the linear as well as the quadratic Stark effect of pentacene in a p-terphenyl crystal [3]. Results on the linear Stark effect in a polymer were obtained by Orrit et al. Some of their investigated terrylene molecules showed a surprisingly strong induced dipole moment [4].
Time Domain Holography
Authors: Rebane Alexander
Published: February 2023

It is acknowledged that inhomogeneous absorption bands consisting of narrow homogeneous zero-phonon lines (ZPL) can be used for the purpose of optical data storage in the frequency dimension /1/. Persistent spectral hole-burning (PSHB) /2,3/ has made it feasible to preserve the recorded frequency domain information for a practically unlimited period of time. Via PSHB the inhomogeneous distribution function of the resonance frequencies of the impurity zero-phonon lines can be altered in an almost arbitrary fashion. This, in turn, makes it possible to manipulate the absorption coefficient and correlated to it index of refraction of the optical storage media. On this basis it has been proposed to use PSHB for the shaping of laser pulses via Fourier synthesis /4/. Holographic storage of time domain optical signals in PSHB media was proposed by Mossberg /5/. In the first experiments on the PSHB time domain holography the reproduction of various temporal shapes of picosecond pulses was demonstrated in dye doped polymers cooled to liquid helium temperature /6/. Earlier Zuikov et al. observed correlation between the temporal shapes of nanosecond excitation laser pulses and photon echo signals /7/. Since that time a variety of experiments on time domain holography in different resonant media have been reported (see /8/ and references therein).
Optical Data Processing Using Photon Echoes
Authors: Samartsev V.V.
Published: February 2023

Our experimental results of the long-lived photon echo’s investigation in LaF3 : Pr3+ - crystal and its optical storage applications and optical processing have been presented.
Holographic Hole Burning
Authors: Renn Alois , Bernet Stefan , Kohler Bern , Wild Urs P.
Published: February 2023

Persistent spectral hole burning (PSHB) [1] allows for frequency selective recording of holograms and opens interesting prospects for high density optical information storage and processing. When hole burning is performed with the interference pattern of two crossed laser beams a spectrally narrow hole is created in an inhomogeneously broadened absorption band and simultaneously the spatial fringe pattern is recorded as a modulation of the hole depth. During reconstruction of the hologram diffraction from this spatial fringe pattern occurs, reflecting the changes of the absorption coefficient and the refractive index introduced by the spectral hole [2].
Optical Modelling of Neural Networks as a Realization of Spectral Hole Burning Distributed Data Storage
Authors: Rebane Karl. K.
Published: February 2023

Optimistic estimates put the limits for PSHB storage up to 1012 bits per cm2 (i.e. 104 spectral holes per each diffraction limited surface pixel of the size of λ·λ=10-8 cm2, λ- wavelength) or 1016 bits per cm3 for a volume storage memory (cell size λ·λ·λ=1012 cm3). Energy transfer between impurities destroys the storage. Interaction is absent at low concentrations, however, the latter may result in critical decrease of the number of impurity moleculess available to burn a hole at a fixed wavelength at a fixed spatial spot. If we assume concentration of non-interacting impurities 1018 molecules per cm3, and the storage density of 1012 bits per cm2 or 1016 bits per cm3, there is only 100 molecules on average to store one bit of information. It is a too small amount because of the fluctuations of the number of molecules per cell [1,2] and references therein.
Molecular Computing: Parallel Binary Additions
Authors: Bernet Stefan , Renn Alois , Kohler Bern , Wild Urs P.
Published: February 2023

Recently experiments have been reported in which logical operations were performed using electric field induced interferences of holograms stored in persistent spectral hole-burning media [1,2]. In principle, the logical operations AND and XOR are sufficient to realize a binary computer [3]. Here a ripple carry full adder [3] for the parallel addition of two sets of 400 binary coded 4-bit numbers is experimentally demonstrated.
Precise Measurement of the Stark Effect with Sub-homogeneous Linewidth Resolution in Eu3+:YAIO3
Authors: Meixner A. J. , Jefferson C. M. , Macfarlane R. M.
Published: February 2023

The photon echo is often the best technique for measuring ultra narrow homogeneous linewidths of an inhomogeneously broadened optical transition for which a higher spectral resolution than the laser bandwidth is required. Homogenous linewidths on the order of one kHz have been measured for Eu3+ and Pr3+ in different host materials at liquid helium temperature from the echo intensity as a function of the delay between the two excitation pulses. These linewidths arc three orders of magnitude narrower than the long term jitter bandwidth of the laser which was used for excitation.1 Here we present a novel spectroscopic method based on the modulation of a 2-pulsc photon echo or a stimulated echo by an externally applied field, for the accurate measurement of frequency shifting perturbations with sub-homogeneous linewidth resolution. This is illustrated by the Stark effect on the 7F0→5D0 transition of Eu3+:YAIO3. The basic idea is that two coherent preparation pulses create an excited state population grating in the frequency domain of an inhomogeneously broadened line, which then gives rise to the echo in the course of the free induction decay of the coherently prepared ions. Since the photon echo can be observed for pulse separations much larger than T2, it is possible to generate frequency gratings which have a periodic spacing smaller than the homogeneous linewidth.2 In the case of a centrosymmetric crystal there are two groups of ions with equal and opposite dipole moments. An applied electric field Es shifts the ground and excited state energy levels through interaction with the electric dipole moments of these states and hence leads to a linear frequency shift,
Ω=δμ⇀⋅E⇀s/ℏ, for the two sets of ions in opposite directions, where
δμ⇀ is the difference between the ground and excited state dipole moments. If the electric field is applied after the first pulse, the two sets of ions accumulate equal and opposite phase shifts Φ = ± Ωt during the time interval, t. The result of the second pulse is that an excited state population grating is created in the frequency domain with a period (t + τ)-1 where t is the time interval between the pulses and τ is the duration of one pulse. Since there arc two sets of ions with opposite phase shifts, we formally get two population gratings, one with the phase Φ = + Ωt and one with the phase Φ = − Ωt. with respect to the population grating that is caused without an applied field.
Correlation between the structure of dye-host systems and hole-burning at elevated temperatures
Authors: Sauter B. , Bräuchle C.
Published: February 2023

Persistent spectral hole-burning is a widely used technique in high-resolution spectroscopy to uncover interactions between organic dye molecules and a solid host. Recently, there has been growing interest in understanding the relation between the structure of dye-host systems and hole-burning at higher temperatures. It has been claimed that one reason for hole formation up to temperatures of about 80 K in some freebase porphine-doped polymeric systems is the suppression of the structural relaxation in the polymer due to the existence of hydrogen-bonding in the matrix1-3). In a different approach we report on dye-surface systems showing high-temperature hole-burning properties. In dye-surface systems organic dye molecules are adsorbed on the heterogeneous surface of γ-alumina (γ-Al2O3) powder to reduce the electron-phonon coupling between dye and host.
Hybrid Optical Bistability with Non-Monochromatic Light in Persistent Spectral Hole-Burning Media
Authors: Schwoerer Heinrich , Gygax Hansruedi , Rebane Alexander , Wild Urs P.
Published: February 2023

The possibility to control by applying external electric field the index of absorption (and correlated to it index of refraction) of low-temperature impurity media can serve, in principle, as basis for opto-electronic devices such as laser beam modulators and optical memories.
Persistent Spectral Hole-Burning in Neutron-Irradiated Sapphire and Diamond Crystals
Authors: Sildos I.
Published: February 2023

For successful application of spectral hole-burning (SHB) phenomenon an intensive search for new materials, where SHB would be performable at room temperature, is going on.
Photon-Gated Spectral Hole Burning in the Zinc Tetraphenylporphine/1-Bromoadamantane System Dispersed in Polymethylmethacrylate.
Authors: Tamura Shin-ichiro , Kishii Noriyuki , Shirai Katsuya , Iwamura Takashi , Asai Nobutoshi , Seto Jun'etsu
Published: February 2023

In photon-gated spectral hole burning, a hole is formed via a higher excited state produced by simultaneous laser irradiation at two different wavelengths1). One is the wavelength-selective light which promotes the ground state molecules to the first excited state, and the other is the gating light which promotes the excited molecules to the higher excited reaction sate. Only the wavelength-selective light is required to read out spectral holes and the recorded holes are not destroyed. Moreover, the gating light pumps the molecules up to the reaction state effectively, which may break through the bottleneck effect and enhance the recording sensitivity.
Electric Field Effect on Hole-Burning Spectra of A Cyanine Dye in Langmuir-Blodgett Films
Authors: Bernard J. , Orrit M. , Personov R. I.
Published: February 2023

Earlier, we reported results of hole-burning experiments on Langmuir-Blodgett films (LBF) doped with resorufin, tetraazaporphin and with a cyanine dye [1-3]. The present paper is devoted to the first investigations of the Stark effect on LBF as probed by persistent hole-burning (some preliminary results were reported in a short letter [4]). In particular, we demonstrate here a new possibility of this technique for the study of chromophore orientation in LBF.
A Comparison of Spectral Holeburning in Fluoride and Silicate Glasses Doped With Nd3+
Authors: Jacquier B. , Macfarlane R. M.
Published: February 2023

Persistent spectral holeburning is known to occur in rare-earth doped silica-based glasses,1-3 where the mechanism is attributed to light induced changes in the coupling of tunnelling systems (TLS) which are characteristic of the amorphous state. A number of hole parameters such as lifetime, saturation depth and temperature dependence of the width, can provide important information on the density of states and dynamics of the TLS. We present the first data on spectral holeburning in a rare-earth doped heavy metal fluoride glass (HMF, Rennes) and compare with data obtained on a silicate glass (ED-2, Owens-Illinois). For this study we have chosen the well known 4I9/2 ← → 4F3/2 transition of the Nd3+ ion whose absorption peaks around 870nm (HMF) and 880nm (ED-2). Previous holeburning and photon echo measurements have been reported on the 4I9/2 ← → 4G5/2 transition of the Nd3+ of bulk ED-2 glass4 and on the 4I9/2 ← → 4F3/2 transition of the Nd3' transition of a pure silica fiber.3,5
Fluorescence Line Narrowing and Hole Burning of Uroporphyrin
Authors: Dian J. , Adamec F. , Ambroz M. , Psencik J. , Vacha M. , Hala J.
Published: February 2023

Uroporhyrin, like other natural porphyrins such as coproporphyrin or protoporphyrin, is an important intermediate occurring in the metabolic pathway to protoheme. These porphyrins are important indicators of pathogenic states in an organism. Luminescence spectra of these molecules consist of (≈ 100 cm–1) broad bands due to an inhomogeneous broadening. Fluorescence line narrowing and hole burning spectroscopies enable to remove an inhomogeneous broadening and high resolution spectra can be obtained (≈ 5 cm–1 and ≈ 0.01 cm–1, respectively). Low temperature optical spectra of coproporphyrin and protoporphyrin in various matrices have been measured [1-4]. The aim of this contribution is to present hole burning and fluorescence line narrowing spectra of uroporphyrin.
Electric Field Effect on Accumulated Photon Echoes in Dye Doped Polymers
Authors: Gygax Hansruedi , Rebane Alexander , Schwoerer Heinrich , Wild Urs P.
Published: February 2023

Persistent spectral hole-burning (PSHB) is a versatile tool to study Stark effect in solids where impurity spectra is strongly inhomogeneously broadened. At liquid helium temperatures impurity homogeneous zero-phonon line widths are small (γhom~10–2-10–4cm–1) and narrow holes can be burnt in the inhomogeneous distribution by illumination with narrow band laser(Δνlaser < γhom) U1- Stark effect alters the shape of narrow spectral holes depending on the Stark shift (splitting) of impurity energy levels, orientation of the impurities, strength and orientation of the electric field, as well as on the properties of the matrix [2].
Spectral Hole Burning In Hyperquenched Films
Authors: Hayes John M. , Kim Wook Hyun , Small Gerald J.
Published: February 2023

An apparatus for the deposition of doped, thin, amorphous films has been developed. This apparatus is based on the hyperquenching technique of Mayer (1). In this technique aqueous aerosol, i.e. water clusters, is expanded through an orifice and deposited onto a cryoplate. In Mayer’s work the aerosol was produced by an ultrasonic nebulizer and transferred with a carrier gas through an aperture and then onto the cryoplate. In our apparatus the aerosol is formed and deposited from a thermospray nozzle source (2). Use of the thermospray nozzle permits formation of films uncontaminated by condensation of a carrier gas and also permits some control of the size of clusters in the aerosol by control of the temperature differential along the source. An important point is that with this hyperquenching technique, vitrification occurs directly from the liquid state, thus facilitating the inclusion of dopants into the film.