Versatile and High-Repetition Subnanosecond Light Source for Fluorescence Lifetime Measurements

Abstract

We describe the construction and emission characteristics of a gap-adjustable, capacitor-replaceable pulsed light source (air-discharge type) that produces high-repetition pulsed UV light of nanosecond duration. Stable light pulses of 0.8 to 3.5 ns width are generated from atmospheric-pressure air discharge between the sharp anode and round cathode. Appreciable heterogeneities on the distribution of emission intensity and its on-set timing along the discharge gap were observed. Fluorescence lifetimes of ethidium bromide solutions were measured to demonstrate the usefulness of the light source.

Two-dimensional spatial distribution of electric-discharge plasma around a frictional interface between dielectric surfaces

“…We have already made it clear that ultraviolet radiation is emitted from an electric discharge, which generates a nonequilibrium plasma of N 2 at the frictional point during scratching of several insulator surfaces by a diamond in air. 18 The absence of spectral line peaks for O 2 in triboluminescence is similar to the absence of photon emission from O 2 in a corona discharge in air, [19][20][21] which has received much attention in applications in plasma chemistry, for example, in NO removal, 22 and in surface treatments. 23 The purpose of this study was to image the electric-discharge plasma on a dielectric surface during friction by measuring the twodimensional spatial distribution of ultraviolet radiation.…”

Long-Lifetime, Nanosecond Gas-Discharge Light Source Utilizing Automobile Spark Plugs as Lamp Electrodes

“…In the previous study, the effects of the gap distance and charging capacitance on the pulse width [full width at halfmaximum (FW HM)], peak intensity, and repetition frequency were examined. 13 In the previous light source (atmospheric pressure air discharge), the minimum duration of the light pulse (less than 0.8 ns) occurred when the gap distance was set to 0.2 m m.…”

“…To over-come these drawbacks, we have previously reported an air discharge lamp that emits high-repetition-rate, subnanosecond UV-pulsed light that is not compromised by rf noise. 13 However, skillful technique is often required to construct the lamp electrode. Also, atmospheric pressure and humidity in¯uence the emission stability, because the electrodes are exposed to the atmosphere.…”

Applications of fluorescence microscopy to studies of dental hard tissue

“…Furthermore, the fluorescence decay curve of each component has its own decay time [27]. Therefore, we have successfully employed time-resolved fluorometry in the dynamic mode for the study of human teeth [7,[28][29][30][31][32].…”

“…The fluorescence was then analyzed with a monochromator and detected with a fast photomultiplier (PM) (R-1635-2; Hamamatsu Photonics, Japan), and the output photocurrent was converted to a digital signal with a 14-bit analog-to-digital converter (ADC) and processed by a computer (PC9801; NEC, Japan). The dynamic fluorescence was obtained under the condition of excitation with a repetitive pulse of ultraviolet light (wavelength = 336 nm, duration = 1 ns, repetition frequency = 10 kHz) generated from an air-discharge lamp [28]. Finally, the fluorescence signal was measured with a time-resolved photon counter (time-correlated single photon counting system, time resolution = 25 ps; model 566 and model 584, EGG and Ortec, USA).…”