3.3.3.110. NXxas_trans

Status:

application definition (contribution), extends NXxas

Description:

In transmission, the linear attenuation coefficient or absorption ...

In transmission, the linear attenuation coefficient or absorption coefficient \(\mu(E)\) is given by the Beer-Lambert law:

\[\mu(E)t = -\ln(I/I_0)\]

where \(I\) is the intensity of the transmitted beam, \(I_0\) is the intensity of the incident beam, and \(t\) is the thickness of the sample.

The top-level intensity field contains the processed absorption coefficient. When the raw detector data and processing steps are available, they can be stored in the optional NXinstrument, NXcollection, and NXprocess groups, enabling full reproducibility of the data reduction.

Symbols:

No symbol table

Groups cited:

NXcollection, NXcrystal, NXdetector, NXentry, NXinstrument, NXmonochromator, NXnote, NXparameters, NXprocess, NXsource, NXsubentry

Structure:

ENTRY: (required) NXentry ⤆

definition: (required) NX_CHAR ⤆

Official NeXus NXDL schema to which this file conforms. ...

Official NeXus NXDL schema to which this file conforms.

Obligatory value: NXxas_trans

intensity: (required) NX_FLOAT (Rank: dataRank, Dimensions: [nP, nEnergy]) {units=NX_ANY} ⤆

The absorption coefficient \(\mu(E)t = -\ln(I/I_0)\).

INSTRUMENT: (recommended) NXinstrument ⤆

The ``data`` field of each detector below holds the intensity ...

The data field of each detector below holds the intensity used to compute the absorption coefficient and may already include corrections. If the uncorrected values are kept, they are archived in the NXcollection group and the corrections are described in NXprocess.

SOURCE: (recommended) NXsource ⤆

type: (required) NX_CHAR ⤆

name: (required) NX_CHAR ⤆

probe: (required) NX_CHAR ⤆

Obligatory value: x-ray

monochromator: (recommended) NXmonochromator ⤆

energy: (recommended) NX_FLOAT (Rank: 1, Dimensions: [nEnergy]) {units=NX_ENERGY} ⤆

crystal: (recommended) NXcrystal ⤆

d_spacing: (required) NX_FLOAT {units=NX_LENGTH} ⤆

The spacing between crystal planes of the reflection

type: (required) NX_CHAR ⤆

Type or material of monochromating substance ...

Type or material of monochromating substance (Si, Ge, Multilayer).

reflection: (required) NX_INT (Rank: 1, Dimensions: [3]) {units=NX_UNITLESS} ⤆

Miller indices (hkl) values of nominal reflection

i0: (required) NXdetector ⤆

Detector measuring the incident beam intensity ...

Detector measuring the incident beam intensity \(I_0\).

data: (required) NX_NUMBER (Rank: dataRank, Dimensions: [nP, nEnergy]) ⤆

itrans: (required) NXdetector ⤆

Detector measuring the transmitted beam intensity ...

Detector measuring the transmitted beam intensity \(I\).

data: (required) NX_NUMBER (Rank: dataRank, Dimensions: [nP, nEnergy]) ⤆

iref: (recommended) NXdetector ⤆

Detector measuring the reference intensity ...

Detector measuring the reference intensity \(I_{ref}\), placed after a reference sample (typically a metal foil). For a reference that is an independent spectrum probing a different absorbing element or absorption edge, use the reference subentry instead.

data: (required) NX_NUMBER (Rank: dataRank, Dimensions: [nP, nEnergy]) ⤆

reference: (optional) NXsubentry ⤆

An independent reference spectrum, for example a metal-foil ...

An independent reference spectrum, for example a metal-foil standard used for energy calibration. Use this group instead of the iref detector when the reference is a complete spectrum in its own right, in particular when it probes a different absorbing element or absorption edge, so that the element, edge, energy axis, and intensity of the reference can be described in full.

Provide the iref detector when the reference is a simultaneous transmission channel that shares the main energy axis. Provide this reference subentry when the reference is an independent measurement. Do not provide both for the same reference.

definition: (required) NX_CHAR ⤆

Official NeXus NXDL schema to which this subentry conforms. ...

Official NeXus NXDL schema to which this subentry conforms. Should be an NXxas-family definition (for example NXxas or NXxas_trans).

COLLECTION: (optional) NXcollection ⤆

Raw data as written by the acquisition software, ...

Raw data as written by the acquisition software, preserved without modification to allow independent reprocessing.

PROCESS: (optional) NXprocess ⤆

Description of how :ref:`intensity ...

Description of how intensity was obtained from the raw detector data (i0, itrans, and iref). When present, it allows a third party to fully reproduce the data reduction.

program: (optional) NX_CHAR ⤆

Name of the program used for processing.

version: (optional) NX_CHAR ⤆

Version of the program used for processing.

date: (optional) NX_DATE_TIME ⤆

Date and time of processing.

sequence_index: (optional) NX_POSINT ⤆

Order of this step when several NXprocess groups ...

Order of this step when several NXprocess groups describe a sequence of corrections.

parameters: (optional) NXparameters ⤆

Validated parameters of the corrections applied, for ...

Validated parameters of the corrections applied, for example energy calibration, deglitching, incident-beam normalization, or scan merging. Each parameter should carry a units attribute where applicable.

note: (optional) NXnote ⤆

Code or notes reproducing the top-level :ref:`intensity ...

Code or notes reproducing the top-level intensity from the raw data.

type: (required) NX_CHAR ⤆

Mime content type of the note data field. ...

Mime content type of the note data field.

Obligatory value: text/x-python

data: (required) NX_CHAR

The reproduction code or notes.

Hypertext Anchors

List of hypertext anchors for all groups, fields, attributes, and links defined in this class.

NXDL Source:

https://github.com/nexusformat/definitions/blob/main/contributed_definitions/NXxas_trans.nxdl.xml