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Impact of composition and ex-situ laser irradiation on the structure and optical properties of As-S-based films synthesized by PECVD
摘要： Synthesis of amorphous chalcogenide As-S-based films with arsenic content from 35 to 55 at. % by a PECVD method is achieved. The composition-structure-optical properties relationship is revealed. Varying the composition of the films from As35S65 to As55S45 is accompanied by a change of the dominant structural units: from AsS3/2 pyramids to cage-like As4S4 and As4S3 units, causing a considerable decrease of the optical band gap from 2.42 to 1.87 eV. It has been found out that modification by a focused laser irradiation (473 nm) leads to formation of micro/nanocrystalline inclusions feasible for applications in medicine, optoelectronics and integrated optics. The type of inclusions depends on the dominant structural units of the initial films. In case of the As55S45 film appearance of the dimorphite crystalline phase (α-As4S3) is observed. The ex-situ laser modification of the As-S films leads to appearance of a photoluminescence emission, and its maximum position shifts from 1.8 to 2.05 eV depending on the initial film stoichiometry.
关键词： Optical properties,Arsenic sulfide,Chalcogenide films,Nanocrystals formation,PECVD
更新于2025-09-16 10:30:52
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Study of dry‐ and wet‐process amorphous arsenic sulfides: Synthesis, Raman reference spectra, and identification in historical art materials
摘要： This paper reports the dry and wet synthetic procedures and characterization by Raman spectroscopy of amorphous arsenic sulfide reference pigments. Reference spectra of two amorphous materials obtained by wet process methods and four dry process references of amorphous arsenic sulfide pigments of known composition are presented and discussed. While all materials present a main band characteristic for the amorphous pigment centered on 341 cm?1, additional small contributions indicate the presence of sulfur, arsenic oxide, and crystalline nano phases embedded in the amorphous matrix. Although only the broad 341‐cm?1 peak is necessary to identify the arsenic sulfide as an amorphous material, the smaller additional features allow for the characterization of the various manufacturing processes and initial materials used. In ideal conditions, these small features also enable to assess the As/S ratio of the studied amorphous arsenic sulfide pigments based on their relative intensity. In this context, the latter reference spectra were used to characterize the amorphous arsenic sulfide pigments and their arsenic to sulfur elemental composition in four 18th‐ to 20th‐century historical samples and compared with scanning electron microscopy with energy dispersive X‐ray semiquantitative analyses. The identification of the amorphous arsenic sulfide used in these historical samples was compared with the description of the manufacturing processes reported in historical sources of the time, allowing for a better understanding of the evolution of the amorphous arsenic sulfide pigments manufacturing methods.
关键词： reference spectra,cultural heritage,pigment characterization,synthesis,amorphous arsenic sulfide
更新于2025-09-09 09:28:46