Capturing the formation of sub-nanometer sized CdS clusters in LTL zeolite

The radiolytic preparation of sub-nanometer sized CdS clusters in LTL-type zeolite crystals in suspension is reported. The growing process of CdS in the zeolite crystals using a γ-ray irradiator (low dose rate) and a pulse electron accelerator (high dose rate) is followed by UV-vis spectroscopy. The pulse electron accelerator equipped with a transient absorption setup allowed the real-time capturing of CdS formed in the zeolite suspension. Two distinct stages during the formation of sub-nanometer sized CdS clusters in the LTL-type zeolite are identified: (i) fast formation of dispersed small oligomers exhibiting a well-defined sharp absorption peak, which is shifted from 292 to 350 nm in the course of the growth process, and (ii) formation of interconnected CdS clusters along the zeolite channels by diffusion-assisted process. Additionally, the presence of sub-nanometer sized CdS clusters in the zeolite channels is confirmed by transmission electron microscopy (TEM). The sub-nanometer sized CdS clusters formed in the LTL-type zeolite suspension exhibit good stability under hydrous conditions, and no coalesce in the presence of water is observed

Assessing written work by determining competence to achieve the module-specific learning outcomes.

This chapter describes lasers and other sources of coherent light that operate in a wide wavelength range. First, the general principles for the generation of coherent continuous-wave and pulsed radiation are treated including the interaction of radiation with matter, the properties of optical resonators and their modes as well as such processes as Q-switching and mode-locking. The general introduction is followed by sections on numerous types of lasers, the emphasis being on todayʼs most important sources of coherent light, in particular on solid-state lasers and several types of gas lasers. An important part of the chapter is devoted to the generation of coherent radiation by nonlinear processes with optical parametric oscillators, difference- and sum-frequency generation, and high-order harmonics. Radiation in the extended ultraviolet (EUV) and x-ray ranges can be generated by free electron lasers (FEL) and advanced x-ray sources. Ultrahigh light intensities up to 1021 W/cm2 open the door to studies of relativistic laser–matter interaction and laser particle acceleration. The chapter closes with a section on laser stabilization