B2/B3: Photoemission & core-level spectroscopy

Introduction

Set of data storage objects to describe photoemission experiments including x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), hard x-ray photoelectron spectroscopy (HAXPES), angle-resolved photoemission spectroscopy (ARPES), two-photon photoemission (2PPE) and photoemission electron microscopy (PEEM). We also included descriptors for advanced specializations, such as spin-resolution, time resolution, near-ambient pressure conditions, dichroism etc.

Application Definitions

We created two new application definitions:

NXmpes:

A general appdef with minimalistic metadata requirements, apt to describe all photemission experiments.

Base Classes

We developed entirely new base classes:

NXelectronanalyser:

A base class to describe electron kinetic energy analizers. Contains the collective characteristics of the instrument such as energy resolution, and includes the following subclasses:

NXcollectioncolumn:

Base class to describe the set of electronic lenses in the electron collection column (standard, PEEM, momentum-microscope, etc.).

NXenergydispersion:

Base class to describe the energy dispersion sytem (hemispherical, time-of-flight, etc.).

NXspindispersion:

Base class to describe the set of electronic lenses in the electron collection column.

NXmanipulator:

A base class to describe the complex manipulators used in photoemission experiments, often with > 4 degrees of freedom, cryogenic cooling and other advanced features.

We developed three base classes to describe data processing, which can be used as subclasses of NXprocess if describing post-processing or as subclasses of NXdetector if describing live, electronics level processing:

NXcalibration:

A base class to describe the 1D calibration of an axis, with a function mapping a raw data scale to a calibrated scale with the same number of points.

NXdistortion:

A base class to describe the 2D distortion correction of an axis, with a matrix mapping a raw data image to a undistorted image.

NXregistration:

A base class to describe the rigid transformations that are applied to an image. May be redundant as they can be described with NXtransformations.

Common Base Classes

We developed two classes that are common to other techniques:

NXlens_em:

A class to describe all types of lenses. Includes electrostatic lenses for electron energy analysers.

NXdeflector

A class to describe all kinds of deflectors, including electrostatic and magnetostatic deflectors for electron energy analysers.

Base Classes Extended in Application Definitions

We use existent base classes in application definitions and add descriptors:

NXaperture

Added fileds to describe analyser apertures and slits.

NXbeam

Adedd fields to describe utrafast laser beams.

NXdetector

Added fields to describe electron detectors (MCP+Phospor screen, delay lines etc.).

NXentry

Added fields to describe an experiment.

NXprocess

Added subclasses and collective processing descriptors.

NXsample

Added descriptors specific to photoemission experiments.

NXsource

Added descriptors for laboratory sources (X-ray, UV lamps) but mostly for ultrafast lasers with complex time structures.

NXinstrument

Added descriptors for the overall resolutions of the experiment (energy, momentum, angular, spatial, temporal).