Femtosecond laser ablation of cadmium tungstate for scintillator arrays

Abstract

a b s t r a c tUltrafast pulsed laser ablation has been investigated as a technique to machine CdWO 4 single crystal scintillator and segment it into small blocks with the aim of fabricating a 2D high energy X-ray imaging array. Cadmium tungstate (CdWO 4 ) is a brittle transparent scintillator used for the detection of high energy X-rays and γ-rays. A 6 W Yb:KGW Pharos-SP pulsed laser of wavelength 1028 nm was used with a tuneable pulse duration of 10 ps to 190 fs, repetition rate of up to 600 kHz and pulse energies of up to 1 mJ was employed. The effect of varying the pulse duration, pulse energy, pulse overlap and scan pattern on the laser induced damage to the crystals was investigated. A pulse duration of Z 500 fs was found to induce substantial cracking in the material. The laser induced damage was minimised using the following operating parameters: a pulse duration of 190 fs, fluence of 15.3 J cm À 2 and employing a serpentine scan pattern with a normalised pulse overlap of 0.8. The surface of the ablated surfaces was studied using scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy and X-ray photoelectron spectroscopy. Ablation products were found to contain cadmium tungstate together with different cadmium and tungsten oxides. These laser ablation products could be removed using an ammonium hydroxide treatment.

Biosynthesis of CdS Quantum Dots Mediated by Volatile Sulfur Compounds Released by Antarctic Pseudomonas fragi

“…Survey spectra of CdS nanoparticles biosynthesized with Cys presented C 1s, Cd 3d, Na 1s, O 1s, P 2p, and S 2p (Supplementary Figure S1A). Cd 3d deconvoluted peaks (Figure 5C) indicated binding energies of 412 and 405 eV, corresponding to Cd 3 / 2 and Cd 5 / 2 as reported by Marusak et al (2016) and Richards et al (2016). Survey spectra of CdS obtained from Met contained similar elements, but it was not possible to identify Cd 3d peaks (Supplementary Figure S1B).…”

“…The presence of N and S suggest that Cys and Met are part of the organic coating of the QDs surface, indicating that these sulfur compounds could be stabilizing the QDs. The Cd 3d spectrum deconvoluted peaks indicated binding energies of 412 and 405 eV, corresponding to Cd 3 / 2 and Cd 5 / 2 , respectively, (Marusak et al, 2016; Richards et al, 2016). Furthermore, the intensity ratio of the Cd 3 / 2 and Cd 5 / 2 peaks was 2:3, confirming that Cd was obtained in the state of Cd 2+ , which is in accordance to what has been previously reported for CdS QDs (Bag et al, 2017).…”

Surface ablation and threshold determination of AlCu4SiMg aluminum alloy in picosecond pulsed laser micromachining

“…Recently, the interaction between the ultrafast pulsed laser and the material surface has become a research hotspot of significant attention due to the rapid development of laser processing technologies [1][2][3][4][5]. Ultrafast pulsed laser ablation exhibits many unique processing advantages, such as high ablation precision and efficiency, more controllable, minimal processing size, and almost no thermal damage and boundary effect, by virtue of its extremely short pulse duration and very high peak energy [4][5][6].…”

Exploring light confinement in laser-processed LYSO:Ce for photon counting CT application

“…There are a number of laser-based techniques being explored for scintillator processing for different applications, including Laser Ablation (LA) [43,44], Laser Induced Optical Barriers (LIOB) [33][34][35][36][45][46][47], and the similar technique of Sub-Surface Laser Engraving (SSLE) [37,38,48]. Common for all the above-mentioned techniques are that they make use of a high power pulsed laser to create structured scintillators in order to achieve light confinement.…”