Laboratory X-ray Emission Spectrometer for Phosphorus Kα and Kβ Study of Air-Sensitive Samples

Abstract

The analytical chemistry of phosphorus-containing materials is often impeded by the long measurement times and relatively large sample masses needed for 31P NMR spectroscopy, by the scarcity and access limitations of synchrotron beamlines operating in the energy range of the P K-edge, by the challenges posed by species interconversion during liquid extraction, and by the considerable air-sensitivity typical of many phosphorus-containing materials and nanophases. To this end, we report the design and operation of a new laboratory-based spectrometer to simultaneously perform P Kα and Kβ X-ray emission spectroscopy (XES) while being housed in a research-grade controlled-atmosphere glovebox. Demonstration studies on nickel phosphide nanophases illustrate the importance of air-free XES and the value of simultaneous Kα and Kβ spectroscopy for identifying the P oxidation state and for investigating nanoscale influences on valence level electronic structure.

Colloidal, Room-Temperature Growth of Metal Oxide Shells on InP Quantum Dots

“…X-ray emission spectroscopy. P Kα and Kβ XES measurements were performed on a laboratory spectrometer, to be described in Abramson, et al 68 , with a design similar to that of Holden et al 69 , and where the methodology of Stein et al 18 was used for estimating the oxidation state. The spectrometer is set up in a N2-filled glove box and uses a low-power, unfocused X-ray tube (Varex VF-80, 100 W) to illuminate the sample, whose emitted X-rays are analyzed simultaneously by two 10 cm radius of curvature cylindrical crystal analyzer and coupled to homemade CMOS direct-exposure color X-ray cameras.…”

“…The two multiplexed spectrometers are tuned to the P Ka and Kb emission energies, respectively. Data collection followed the methodology from Abramson, et al 68 InP QD samples were dropcast onto Si wafer with a spot size of ~5 mm diameter. The Kα emission spectra were analyzed using linear combination fitting with the nonlinear least-squares fitting Python package LMFIT.36 (described in more detail in Stein et al 18 ).…”

Colloidal, Room Temperature Growth of Metal Oxide Shells on InP Quantum Dots

“…X-ray emission spectroscopy. P Kα and Kβ XES measurements were performed on a laboratory spectrometer, to be described in Abramson, et al 72 , with a design similar to that of Holden et al 73 , and where the methodology of Stein et al 18 was used for estimating the oxidation state. The spectrometer is set up in a N2-filled glove box and uses a low-power, unfocused X-ray tube (Varex VF-80, 100 W) to illuminate the sample, whose emitted X-rays are analyzed simultaneously by two 10 cm radius of curvature cylindrical crystal analyzer and coupled to homemade CMOS direct-exposure color X-ray cameras.…”

“…The two multiplexed spectrometers are tuned to the P Ka and Kb emission energies, respectively. Data collection followed the methodology from Abramson, et al 72 InP QD samples were dropcast onto Si wafer with a spot size of ~5 mm diameter. The Kα emission spectra were analyzed using linear combination fitting with the nonlinear least-squares fitting Python package LMFIT.36 (described in more detail in Stein et al 18 ).…”