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https://github.com/angelo-peronio/nanonis-xarray

Xarray plugin to read Nanonis spectroscopy .dat files
https://github.com/angelo-peronio/nanonis-xarray

afm dat mimea nanonis physics python specs sps stm stm-iets sts surface-science xarray

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Xarray plugin to read Nanonis spectroscopy .dat files

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# Xarray plugin to read Nanonis spectroscopy .dat files

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`nanonis-xarray` is a [`xarray`](https://xarray.dev/) plugin to read spectroscopy measurements saved in text
format (`.dat`) by a [Nanonis Mimea](https://www.specs-group.com/nanonis/products/mimea/)
SPM control system from [SPECS Surface Nano Analysis GmbH](https://www.specs-group.com/).

The data is read into a [`xarray.Dataset`](https://docs.xarray.dev/en/stable/getting-started-guide/why-xarray.html#core-data-structures), where each measured channel (tunnelling current, AFM oscillation amplitude, …) is a [`xarray.DataArray`](https://docs.xarray.dev/en/stable/user-guide/data-structures.html#dataarray) with up to three dimensions:

* The independent variable of the measurement, such as sample bias voltage or tip z position;
* The sweep number, if the measurement has been repeated multiple times;
* The sweep direction (forward or backward), if the independent variable has been swept in both directions.

```python
>>> import xarray as xr

>>> data = xr.open_dataset("tests/data/z.dat")
>>> data.coords
Coordinates:
* z_rel (z_rel) float64 2kB [m] -2.1e-10 -2.065e-10 ... 4.865e-10 4.9e-10
* sweep (sweep) uint32 12B 1 2 3
* direction (direction) category 18B fw bw

```

[`pint-xarray`](https://xarray.dev/blog/introducing-pint-xarray) is used to associate a physical unit to each channel, unless `xr.open_dataset()` is called with `quantify_vars=False`:

```python
>>> data["current"].pint.units

```

The header of the measurement is stored in the `attrs` nested dictionary:

```python
>>> data.attrs["Z Spectroscopy"]["Number of sweeps"]
3
>>> data.attrs["Z Spectroscopy"]["backward sweep"]
True

```

Physical quantities are stored as [`pint.Quantity`](https://pint.readthedocs.io/en/stable/getting/tutorial.html#defining-a-quantity), timestamps as [`datetime.datetime`](https://docs.python.org/3/library/datetime.html#datetime-objects), and paths as [`pathlib.Path`](https://docs.python.org/3/library/pathlib.html#basic-use):

```python
>>> data.attrs["NanonisMain"]["RT Frequency"]

>>> data.attrs["Date"]
datetime.datetime(2015, 3, 27, 11, 49, 5)

```

## 🚧 Work in progress 🚧

This library is under development: expect breaking changes. Nanonis binary formats (`.sxm`, `.3ds`) are currently not supported, and can be read by similar projects:

* [`nanonispy2`](https://github.com/ceds92/nanonispy2)
* [`xarray-nanonis`](https://github.com/John3859/xarray-nanonis)
* ... and [many more](https://pypi.org/search/?q=nanonis).

## How to cite

Cite `nanonis-xarray` in your published work using the metadata in [`CITATION.cff`](CITATION.cff).
Specific DOIs and BibTeX entries for each released version can be found on [Zenodo](https://doi.org/10.5281/zenodo.17095214).