Time-resolved Photon Emission Research Articles

Machine Learning for Time-Resolved Emission: Image Resolution Enhancement

Abstract This article describes a novel method for improving image resolution achieved using time-resolved photon emission techniques. Instead of directly generating images from photon counting, all detected photons are displayed as a point cloud in 3D space and a new higher-resolution image is generated based on probability density functions associated with photon distributions. Unsupervised learning algorithms identify photon distribution patterns as well as fainter emission sources.

Time-resolved ultra-weak photon emission as germination performance indicator in single seedlings

As they grow, plant seedlings emit very small amount of light, the so-called ultraweak photon emissions (UPE). Numbering tens or hundreds of photons per second, this UPE radiation has been measured on groups of 10 to 1000s of seedlings growing together. Here, we set out to measure UPE on single germinating seeds, enabling the assessment of individual seeds. Here, UPE were measured in low-noise laboratories, enabling long-term, stable and reproduceable testing conditions. UPE recordings could in effect be performed on single germinating seedlings of mung beans, corn and wheat, also comparing measurements to 10-seed sample of mung beans. The data reveal differences between seedlings and plant species. The relation between the seedling's development – total length of roots plus leaflet - and the UPE data is presented in terms of the total photon counts as a function of seedling growth in time. These data were fitted in linear interpolation, for the tests with mung beans when related to the UPE slope (R2 ~0.834). UPE versus growth correlation was weaker for tests conducted with single mung seedlings (R2 <0.4), revealing individual variation and seedling movements during growth. For single corn, intermediates correlation coefficients R2 were observed (0.57<R2 <0.83), while single wheat seed data were more sparse (R2~0.62). Altogether the data show a general pattern of linear UPE to growth relationship, yet highlighting variations between plant species, which provide a benchmark for assessing the health of early seedlings.

Photon, Electron and Secondary Ion Emission from Single C(60) keV Impacts.

This paper presents the first observation of coincidental emission of photons, electrons and secondary ions from individual C(60) keV impacts. An increase in photon, electron and secondary ion yields is observed as a function of C(60) projectile energy. The effect of target structure/composition on photon and electron emissions at the nanometer level is shown for a CsI target. The time-resolved photon emission may be characterized by a fast component emission in the UV-Vis range with a short decay time, while the electron and secondary ion emission follow a Poisson distribution.

Volume-conserved Twist Excited-state of π-Conjugated Molecules

The excited state characters of HY103 have been studied by means of time-resolved photon emission (time-correlated single photon counting) and time dependent density functional theory calculations. The experimental and theoretical results demonstrate that HY103 dyes undergo an efficient one-bond-flip motion after photoexicitation at room temperature, which leads to a very short lifetime of the normal fluorescence state, and a weak fluorescence emission around 670 nm. However, when HY103 are excited in amorphous glasses at 77 K, the normal fluorescence emission is prolonged to nanoseconds time scale about 2 ns, and the fluorescence emission is enhanced. Furthermore, a new emission state is produced, which is characterized as a volume-conserved twisted (VCT) state. This is the first observation of a VCT state. The experiment indicates that the VCT motion of excited state of π-conjugated molecules in restricted environment can form a stable emission state, and the excited state character of π-conjugated molecules in restricted environment is complex.

Reduction of the acquisition time for CMOS time-resolved photon emission by optimized IR detection

We have achieved a greater than 2.5× improvement in the acquisition time figure of merit of an EmiScope™ Time Resolved photon Emission (TRE)-based probe system, by optimization of the detector dark-count rate, photon detection efficiency, and timing jitter. The effects of detector after-pulsing were reduced by use of an optimized hold-off time.

Implementation of TRE systems into Emission Microscopes

Time-Resolved photon Emission (TRE) has the potential to identify faults by analysing the luminescence emission, as a function of time. TRE detectors provide time capabilities, but they have the disadvantage to be a single-point measurement, with no possibility to spatially map the luminescence emissions from the chip. In order to first localize the luminescence origin (e.g. a switching transistors or a faulty device within a chip), it is interesting to couple TRE equipments (i.e. time information) with light emission microscopes (i.e. spatial information). In this paper, we present a quantitative comparison of various commercially-available TRE detectors and photon counting electronic modules. From the analysis of the best solution, we propose a cost effective solution for the implementation of a TRE detector into a commercial emission microscope, with no hardware modifications.

Time Resolved Photon Emission Processing Flow for IC Analysis

IC analysis can be facilitated using Time Resolved Photon Emission (TRE). Because recent technologies work at ultra low power supply voltages: <1V, background noise can mask commutation peaks thus biasing analyses. With a positive photon discrimination flow, signals can be extracted even below the noise level. However signal extraction depends on various parameters (e.g., bin size, cutoff frequency). WE have developed a photon discrimination technique to optimize these parameters. This technique is integrated into a generic method which takes advantage of static light emission acquisition for identifying switching transistors and which links TRE measurements to simulations for optimal IC diagnostics.

Light Emission From Small Technologies. Are Silicon Based Detectors Reaching Their Limits?

After a brief review of light emission in field effect transistors, we extract some electrical and physical parameters linked to the emission of photons such as VDD and channel length. Using 120nm technology structures (nMOS, pMOS, inverters...) we compare emissions with the following detectors: CDD, MCT for static emission, PICA, SiAPD and SSPD for time resolved photon emission (TRE). Results are interpreted according to the quantum efficiency of detectors as a function of wavelength. Finally, the wavelength shift is addressed by confronting practical results with earlier publications on light emission spectra.

Time-Resolved Measurements of Self-Heating in SOI and Strained-Silicon MOSFETs Using Photon Emission Microscopy

A simple noninvasive optical technique for characterization of self-heating dynamics in advanced metal-oxide-semiconductor field-effect transistors is reported for the first time. The technique uses time-resolved photon emission microscopy to measure the temperature-dependent luminescence of off-state leakage current. It measures the temperature of the device channel, independent of surrounding materials or interconnects. The technique has been used to measure, for the first time, self-heating dynamics in silicon-on-insulator and strained-silicon n-field-effect transistors.

Photon emission accompanying deformation and fracture of ice

We observed photon emission during deformation and fracture of axially loaded polycrystalline ice. Emission of visible photons (300–650 nm) was correlated with crack generation and fracture, based on time-resolved photon emission signals taken during load changes. Emission intensity, including the entire spectra ranging from 300 to 650 nm, was roughly correlated with increasing strain energy released by fracturing, while considerable scattering of the intensity data implied that emission intensity also depended on the characteristics of each individual crack. Correlation was taken between simultaneous emissions detected with two photomultiplier tubes with different ranges of spectral sensitivity. Brief, intense emissions were clearly associated with load drops, and these probably included wavelengths shorter than 320 nm, indicating that near ultraviolet light is also emitted. On the other hand, weak but continuous signals with wavelengths longer than 650 nm were emitted the entire time the ice was subjected to a load. Emission intensity and spectra may be attributed to microprocesses during fracturing. Experimental evidence for emission of visible photons indicates that the generated electric charges on crack surfaces and at crack tips have energy ranging from 2 to 6 eV. PACS No.: 46.50

Time-resolved photon emission from layered turbid media

We present numerical and experimental results of time-resolved emission profiles from various layered turbid media. Numerical solutions determined by time-resolved Monte Carlo simulations are compared with measurements on layered-tissue phantoms made from gelatin. In particular, we show that in certain cases the effects of the upper layers can be eliminated. As a practical example, these results are used to analyze in vivo measurements on the human head. This demonstrates the influence of skin, skull, and meninges on the determination of the blood oxygenation in the brain.