Infrared Stimulation Research Articles

The evolution of Buctouche Spit, New Brunswick, Canada

Buctouche Spit is an 11-km long sandy spit on the northeast shore of New Brunswick, Canada. It is a typical flying spit, having a narrow proximal section which is characterized by a single foredune that is prone to overwash and transgression, and a much wider prograding distal section which is characterized by a well-developed foredune backed by a series of relict foredunes. An optical-luminescence dating method in which infrared stimulation is used on potassium feldspars was developed for this study. It is a very promising method for dating Holocene deposits, yielding good resolution and having simplicity of measurement. The luminescence ages obtained indicate that Buctouche Spit extended at a rate of ~4 m yr −1 between 715 ± 45 years ago and 240 ± 25 years ago. This extension rate equates to a distal end accumulation rate of ~ 56,000 m 3 yr −1 for this period. At this rate of accretion, the present Buctouche Spit would have formed during the past 2000 years. The core data indicate that the spit is ⩾2200 years old, which is consistent with the preceding estimate. Since 240 ± 25 years ago, the rate of sediment accumulation at Buctouche Spit has apparently been falling. The accumulation rate between 1839 and 1945 was ~23,000 m 3 yr −1, less than half of the historic rate of ~56,000 m 3 yr −1. Since 1945, the distal end of Buctouche Spit has not prograded/extended measurably. This is because Buctouche Spit's present vertical growth rate is, at most, equal to the rate of relative sea-level rise at the spit and may be as little as half of the rate of relative sea-level rise. Present sediment supply to Buctouche Spit is probably < 16,000 m 3 yr −1. It is likely that the much larger sediment supply required to sustain an historic accretion rate of ~ 56,000 m 3 yr −1 was derived from the reworking of a former sandy barrier located seaward, and possibly updrift of, the present spit. Buctouche Spit is now in a limited sediment supply situation and it has become a constrained spit. Sediment is being eroded from the centre section of the spit, transported to the distal end, and then carried away by ebb-tidal currents. The centre section of the spit will likely breach within the next hundred years. If a breach (or breaches) becomes permanently established in the centre section of the spit, the distal end will suffer significant erosion and may be destroyed. After this, the cycle of rebuilding and landward migration would likely start again at a new location landward of the present spit as relative sea level continues to rise. It is concluded that the key to understanding Buctouche Spit's long-term evolution is recognizing that it is migrating landward both by continuous processes like overwash, and by the more discrete and catastrophic process of overstepping.

Comparison of the green- and infrared-stimulated luminescence of feldspar

The differences are highlighted of various aspects of behaviour of the luminescence signal from feldspar when stimulated by green light and when stimulated by infrared radiation. In respect of bleaching, a comparison is made of the influence of white light (daylight) on the two stimulated luminescence signals, as well as a comparison of the influence of infrared exposure on the green-stimulated signal with the influence of green exposure on the infrared-stimulated signal. The influence of preheating on the two stimulated signals is also compared. Light-emitting diode systems were used for both green and infrared stimulation. The observations are considered in relation to the mechanism relevant to green- and infrared-stimulated luminescence from feldspar.

Photostimulated luminescence excitation spectroscopy of feldspars and micas

Although much photostimulated luminescence (PSL) work has been with broad-band or monochromatic stimulation sources, both excitation and emission spectroscopy are fundamentally important to characterize the underlying physical processes and develop robust application methods. This paper discusses the results of excitation spectra obtained from a series of irradiated feldspar and mica samples stimulated from 450 to 1200 nm using a scanning spectrometer. Spectra from 450 to 950 nm were stimulated using a 300 W Cermax Xe lamp, supplemented from 700 to 1200 nm with a tungsten-halogen lamp. Samples were illuminated through beam production optics coupled with an f3.4 stepping motor-driven monochromator in conjunction with a series of long-pass filters. A filtered bialkali photomultiplier in photon counting mode was used to record PSL. Spectra were recorded at various sample temperatures, at a range of doses from 1 Gy to 10 kGy, and after pulsed annealing and monochromatic bleaching cycles to establish thermal stabilities and inter-band coupling. The instrument response was characterized by pyroelectric radiometry. Detailed spectroscopic studies were made to a pure microcline feldspar and an International Atomic Energy Agency (IAEA) secondary reference feldspar (AQCS F1). Additional measurements were taken from a range of 19 alkali feldspars, two plagioclase feldspars and nine mica samples of known geological origin and age. All samples showed a range of visible to infrared stimulation bands, in proportions that varied from sample to sample. After normalization for spectrometer response, using a pyroelectric radiometer, the positions, shapes and relative intensities of the broad stimulation bands were revealed. A typical sample had bands at 500–540 nm, 550–650 nm and 800–1000 nm. There was evidence of higher-sensitivity blue and near-ultraviolet stimulation bands. Spectra recorded at different sample temperatures, and during thermal ramps, provide clear evidence of thermal assistance to infrared and 550–650 nm visible bands. Activation energy estimates were obtained by Arrhenius analysis of the results. Pulsed annealing experiments and monochromatic bleaching experiments demonstrate coupling between infrared-stimulated PSL and the majority of the green-stimulated signal. They also raise questions about the long-term stability of infrared-stimulated signals. A more stable signal can be obtained within the green stimulation band, which is thermally separable from the infrared-associated component. Although the results reproduce some of the features of the Hütt and Jaek model for feldspars, there are additional features which require a more complex level scheme. The observation of stable centres available to the green band after thermal washing, and of more intense blue-ultraviolet bands suggests that these regions may be more promising than infrared stimulation for dating events of age greater than 10 4–10 5 years.

Luminescence dating of sediments from Buctouche Spit, New Brunswick

In this paper we describe our efforts to determine the formation chronology of a sequence of dunes on Buctouche Spit, a Holocene deposit on the northeast coast of New Brunswick. Optical dating, using infrared stimulation of K-feldspar grains, yielded ages ranging from 5 ± 30 a for an embryo dune to 765 ± 45 a for the oldest dune. Thermoluminescence ages, although less precise, support the recent formation of the dunes. The ages exhibit the expected sedation from youngest to oldest and are consistent with historical evidence coupled with an assumed constant sediment aggradation rate. The age resolution obtained was very good and we conclude that the optical dating method used here shows great promise.

Tests for optically stimulated luminescence from tephar glass

Glass (4–11 μm) samples from 15 volcanic ash deposits were examined for their suitability for optical dating. The samples ranged in age from 8 to 500 ka. Only very weak luminescence was observed using 514 nm (green). 633 nm (red) and ≈880 nm (near infra-red) stimulation. An equivalent dose of 29 Gy was obtained for Mazama ash using near infra-red stimulation. This result agrees well with that obtained earlier using thermoluminescence and is correct for its age of 7.7 ka.

Luminescence dating of the loess profile at Dolní Vestonice, Czech Republic

Thermoluminescence (TL) and Infra-red Stimulated luminescence (IRSL) studies were carried out on 21 samples from loess profiles at Dolní Vestonice. The IRSL measurements gave systematically lower equivalent doses (EDs) than the TL measurements; this could be due to inadequate preheat being applied to the former. Dose rate intercomparisons confirm the view that alpha counting should be carried out on finely ground material. Comparison of ED determination by regeneration and additive dose methods did not suggest sensitivity increases on bleaching, but for the older samples the TL ages were underestimated compared with the expected ages based on the correlation of palaeosol stratigraphy with the framework provided by the deep sea oxygen isotope record. Using the hypothesis of luminescence decay with a lifetime of 150 ka suggests that the previous ages assigned to the palaeosols may not be correct.

COCHISE: laboratory studies of atmospheric IR chemiluminescence in a cryogenic environment

The design of the Cold Chemiexcitation Infrared Stimulation Experiment (COCHISE) facility, a cryogenic apparatus used for laboratory studies of high-altitude infrared excitation phenomena, is presented. The basic design concept is the extensive reduction of thermal background radiation through cryogenic (20 K) cooling of the entire reaction volume and detection system. Vibrationally excited molecules (e.g., NO, O3, CO) are formed in a low-pressure environment by interaction of a flowing reactant gas with discharge-produced radical and/or metastable species; the resulting IR radiation is detected with minimal interference from relaxation and surface effects. A long-path optical system and cryogenic monochromator permit high sensitivity for vibrationally excited species (~105 molecules cm−3) and excellent spectral resolution (~2 cm−1) over the 2–16-μm spectral range. The design and operation of the facility are described in detail. Specific applications of the facility to investigations of IR atmospheric phenomena are also discussed.

Apparent discrepancy between single-unit activity and [14C]deoxyglucose labeling in optic tectum of the rattlesnake.

Autoradiographic analysis of [1-14C]2-deoxy-D-glucose-6-phosphate ([14C]2-DG-P) accumulation in the rattlesnake brain stem and optic tectum was used in an effort to map infrared and visual neuronal pathways. Visual stimulation with a standard stimulus (a heat lamp) resulted in dense labeling of the superficial layers of the optic tectum. Infrared stimulation with the same standard stimulus resulted in labeling at the first synaptic relay, the lateral descending nucleus of the trigeminal tract (LDN-V), but not at higher levels, including the optic tectum. Systematic comparison of electrophysiological properties of tectal neurons was performed using the standard stimulus. Responses of infrared units in one hemitectum and visual units in the other, elicited by the same stimulus used in the [14C]2-DG-P experiments, were analyzed. There were no clear differences in the number, maximal density, spread, or rates of accommodation of visual units and infrared units, although the locus of maximal density was more superficial for visual units. In general, infrared units generated a greater number of action potentials than did visual units. All infrared units responded only to onset of the stimulus but they varied greatly in their ability to maintain discharge for the full duration of the stimulus. Most visual units exhibited on-, off-, or on-off responses. Four units showed only inhibition of spontaneous activity during the visual stimulation. There were significant differences in the evoked responses elicited by visual and infrared stimulation in response to the standard stimulus. Infrared stimuli generated single, large, triphasic on-responses, whereas visual stimulation generated complex multiphasic and long-lasting on- and off-responses. The major infrared on peak reached maximal amplitude at greater depths and was larger than the major visual on peak. Amplitude of the infrared peak fell off more rapidly with distance from the locus of its maximum than did amplitude of the visual peak. These observations are consistent with the view that infrared stimulation is effective in discharging neurons but is not associated with intense synaptic excitation. In contrast, visual stimulation apparently does produce intense synaptic activity, as suggested by the duration, complexity, and spread of the visual evoked response. Failure of this synaptic activity to produce more spikes in visual units probably reflects either depolarizing spike inactivation or the admixture of excitatory and inhibitory actions. Our observations suggest that 2-deoxy-D-glucose uptake is not necessarily correlated with the degree of action potential activation of specific neuronal pathways. The amount of [14C]2-DG-P labeling may reflect the metabolic requirements for support of synaptic depolarization as well as that supporting action potentials.

Stimulated luminescence of KI single crystals

Luminescence is observed in KI with red and/or infrared stimulation after previous uv preexposure. The results indicate the onset of band-to-band transitions and provide evidence for the thermal dissociation of self-trapped excitons. A commonly observed emission in KI at 3.0 eV is observed through stimulation. A model for this emission is presented.

ChemInform Abstract: ON INFRARED STIMULATED DURYL RADICAL FLUORESCENCE IN RIGID SOLUTIONS OF DURENE IN 3‐METHYLPENTANE AT 77 K

Chemischer InformationsdienstVolume 4, Issue 49 Physical Organic Chemistry ChemInform Abstract: ON INFRARED STIMULATED DURYL RADICAL FLUORESCENCE IN RIGID SOLUTIONS OF DURENE IN 3-METHYLPENTANE AT 77 K F. P. SCHWARZ, F. P. SCHWARZSearch for more papers by this authorA. C. ALBRECHT, A. C. ALBRECHTSearch for more papers by this author F. P. SCHWARZ, F. P. SCHWARZSearch for more papers by this authorA. C. ALBRECHT, A. C. ALBRECHTSearch for more papers by this author First published: December 4, 1973 https://doi.org/10.1002/chin.197349065AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume4, Issue49December 4, 1973 RelatedInformation

Central response to infra-red stimulation of the pit receptors in a crotaline snake, Trimeresurus flavoviridis.

ABSTRACT Both action potentials and evoked potentials were recorded from the tectum opticum of a crotaline snake, Trimeresurus flavoviridis, in response to infra-red stimulation of the facial pit organs. Action potentials from single units were recorded throughout the tectum. Most units responded to contralateral stimulation, while some responded to both ipsi- and contralateral stimulation. Firing patterns were tonic, phasic, or phasic-tonic, depending on the position of the stimulus and the type of unit being recorded. Sensitivity to stimulus movement was observed. All potentials differed from peripheral potentials in firing patterns. Firing frequency was directly proportional to stimulus intensity. Measurements were made of the vertical and horizontal response fields of single units. Background discharge was noted in all units and its nature discussed. The integrative function of the tectum in regard to infra-red perception was also discussed, as well as the possibility of stereoscopic perception.

Infra-red luminescence of zinc and cadmium sulphide phosphors and the possible role of cation vacancies

Some of the outstanding difficulties of the interpretation of the banded emission spectra (13-22 μm range) in zinc and cadmium sulphide in terms of internal transitions within the Cu2+ ion are discussed. Determinations of the decay times for the infra-red emission in cadmium sulphide for various exciting conditions at different temperatures confirmed that these difficulties exist. It is proposed that the cation vacancy may constitute the luminescence centre and an LCAO-MO treatment is developed to provide quantitative evidence for this argument. By combining experimental and theoretical results it was possible to derive two models for the vacancy which adequately explain all the infra-red emission and absorption properties of this centre. A description of energy level models in terms of the many-electron wave function approach provides a much more realistic account of luminescence centres than the one-electron functions normally adopted. The vacancy models are self-consistent and are flexible enough to explain many of the observations of infra-red stimulation and quenching effects of visible luminescence in zinc sulphide.

Infrared fluorescence of copper-activated zinc sulphide phosphors

An infrared fluorescence was observed for ZnS : Cu, Al and ZnS : Cu, Ga at 1.57μ and 1.72μ. This emission appeared to be excited at low temperatures by radiation of 1.38μ and between 0.5μ and 0.8μ, provided that the phosphor was excited by 3650 Å. The infrared quenching of the visible fluorescence and an infrared stimulation of the visible phosphorescence show a spectrum analogous to the infrared excitation spectrum, and seem to be connected with the same transitions.

Electroluminescence and Thermoluminescence of ZnS Single Crystals

Electroluminescence, thermoluminescence, and thermoluminescence under an applied voltage have been studied in ZnS single crystals. For electroluminescent crystals, the application of a constant electric field during thermoluminescence generally increases the intensity of the emitted light over the sum of the intensities due to the thermoluminescence and to the electroluminescence separately. A similar effect was observed during phosphorescence and during infrared stimulation. No such effects were observed on non-electroluminescent crystals. It was also found that an electric field can fill electron traps, but field emptying of traps did not appear to be important.The current during the electroluminescence and during the thermoluminescence was measured simultaneously with the light emission. There was little correlation between current and thermoluminescence, but quite good correlation between current and the additional light resulting from a constant voltage during the thermoluminescence. These results suggest that some of the electrons released from traps contribute to the current and can cause impact excitation or ionization, but that others are not effective in this. Since both the current and the additional light are considerably higher during the high-temperature glow peak than during the low-temperature one, it appears that the electrons released from the deeper traps are more effective in these processes than those released from the shallower traps.

I. Infra-Red Luminescence of Zinc and Cadmium Sulphide Phosphors

ABSTRACT New luminescence emission bands have been found in the infra-red region at 1-8 μ for cadmium sulphide phosphors. The emission is analogous to that recently found for zinc sulphide phosphors at 1.6μ A systematic study has been made of the infra-red emission in a large number of zinc sulphide, zinc-cadmium sulphide and cadmium sulphide phosphors. It is excited by raising electrons from, the valence band of the phosphor lattice into the ground states of the normal luminescence centres. The latter are either empty in the normal state, or must first be emptied by suitable excitation giving rise to the well-known visible and near visible luminescence of these phosphors. The return of electrons to the valence band gives rise to the infra-red emission. The excitation spectra for the infra-red emission correspond to the quenching spectra for the visible luminescence and for the photoconduction of the above phosphors. A new infra-red stimulation band of the visible emission of ZnS has been found at about 2.55μ, which may well correspond to the single thermal glow peak of these phosphors.

Sensitivity of the cat's eye to infra-red radiations.

THE sensitivity of the eyes of nocturnal animals to infra-red radiations has long been a matter of much speculation. Sensitivity into the far infra-red has been claimed by Vanderplank1 for the owl—an animal with a rod retina; Matthews and Matthews2, however, working on the same animal, did not find any retinal action potentials in response to infra-red stimulation, and Hecht and Pirenne3, who were using the pupillo-motor response of the owl's eye as an index of wave-length sensitivity, found no observable contraction in response to stimulation with infra-red radiations of an energy content of 5 × 106 times that of green light, which produced a marked iris contraction.

Decay in Brightness of Infra-Red Sensitive Phosphors

An equation is derived for the decay in brightness of infra-red (IR) sensitive phosphors under constant IR stimulation. The derivation is based on a second-order process, but takes into account the absorption of the stimulating IR and the emitted visible light. The theoretical curves obtained differ markedly from the simple second-order decay curve, especially when the IR absorption is greater than the visible absorption. The equation involves three arbitrary constants which depend on the quantum efficiency, the number of active centers, and the absorption coefficients of the phosphor for visible and infra-red radiation. The equation is shown to fit the decay curve of a strontium selenide phosphor for an effective decrease in brightness of ${10}^{5}$. It is shown that theories involving a distribution of electron traps, with or without interaction, lead to conclusions that do not agree with the experimental results. Some experimental evidence is offered indicating that there is no change in the trap distribution as this phosphor is exhausted. The apparent deepening of the traps as the decay process continues can be attributed to the absorption of the infra-red.

Light Sum of Phosphors under Thermal and Infra-Red Stimulation*

The experiments reported deal with the recently discovered type of phosphor that shows a large amount of luminescence of visible light when irradiated with infra-red. The emission can be made to occur when the normal phosphorescence has decayed to a negligible value. The light sum, or area under the decay curve, of such phosphors under infra-red stimulation is of the order of 1000 microlambert minutes. Measurements are reported for the light sum when the sample is irradiated with infra-red and when it is heated. In some phosphors the infra-red light sum is from 15 to 30 times as great as the light sum obtained by heating. In others, it is about the same, or perhaps even less. Attention is called to the connection between these experiments and the “glow curve” experiments used to determine the distribution of electron traps in phosphors.