docs: add examples for Mu calculation

docs/source/examples/examples.rst

@@ -12,3 +12,4 @@ Landing page for diffpy.utils examples.
     resample_example
     parsers_example
     tools_example
+    mu_calc_examples

docs/source/examples/mu_calc_examples.rst

@@ -0,0 +1,123 @@
+.. _mu calc Example:
+
+:tocdepth: -1
+
+X-ray Absorption Coefficient (μ) Examples
+#########################################
+
+These examples will demonstrate how to calculate the X-ray absorption
+coefficient, μ, using different methods provided in ``diffpy.utils``.
+
+
+.. admonition:: Methods for obtaining X-ray absorption coefficient
+
+   Obtaining μ can be done in **two
+   different ways** using ``diffpy.utils``.
+
+   1. **Using a "z-scan" measurement**: Perform a z-scan measurement
+      on the sample and use ``diffpy.utils.tools.compute_mud`` to calculate
+      μ.
+   2. **Using tabulated values**: Given composition, density, and X-ray energy,
+      use ``diffpy.utils.tools.compute_mu_using_xraydb`` to calculate μ from
+      tabulated values.
+
+Why is μ Important?
+-----------------------
+
+The X-ray absorption coefficient, μ, quantifies how much X-ray
+radiation is absorbed by a material per unit length. It is a critical
+parameter in many scientific techniques.
+
+For example, when calculating pair distribution functions (PDFs)
+using ``diffpy.pdfgetx``,
+a key assumption is that the X-ray absorption is negligible.
+This is frequently the case for high-energy X-rays. However,
+this must be corrected for when using low energy X-rays, such
+as those from a laboratory source. To correct for X-ray absorption,
+the X-ray absorption coefficient, μ, must be known.
+
+.. admonition:: Correcting for X-ray Absorption with ``diffpy.labpdfproc``
+
+   If your objective is to correct for X-ray absorption in PDF calculations,
+   please refer to our package ``diffpy.labpdfproc``. This package is specifically
+   designed to correct your laboratory X-ray PDF data for absorption effects.
+   More information can be found in the
+   `diffpy.labpdfproc documentation <https://www.diffpy.org/diffpy.labpdfproc//>`_.
+
+
+Calculating μ from a "z-scan" Measurement
+-----------------------------------------
+
+.. note::
+
+   The data we will be using for this example can be found here,
+   `FIXME <https://www.diffpy.org/diffpy.utils/examples/zscan_example_data.txt>`_.
+
+A "z-scan" measurement is the measured transmission of your X-ray incident beam
+as a function of sample position. This is obtained by moving the sample
+along the X-ray beam (z-direction) and recording the transmitted
+intensity at each position. This measured data looks something like this,
+
+.. image:: ../images/FIXME
+   :alt: Example of a z-scan measurement.
+   :align: center
+   :width: 200px
+
+Using this z-scan data, you can calculate **μ·d**, where d is the inner diameter of
+your sample capillary. To do this, simply pass your z-scan measurement to the ``compute_mud``
+function from the ``diffpy.utils.tools`` module.
+
+
+First, import the ``compute_mud`` function,
+
+.. code-block:: python
+
+   from diffpy.utils.tools import compute_mud
+
+Next, pass the filepath to the function,
+
+.. code-block:: python
+
+   filepath = "zscan_example_data.txt"
+   capillary_diameter = 0.5 # mm
+   mud = compute_mud(filepath)
+   print(f"Calculated mu*d: {round(mud, 3)}")
+   print(f"Calculated mu: {round(mud / capillary_diameter, 3)} mm^-1")
+
+This will output the calculated value of μ·d, which is unitless, and μ in mm\ :sup:`-1`.
+
+.. code-block:: console
+
+   Calculated mu*d: FIXME
+   Calculated mu: FIXME mm^-1
+
+Calculating μ from Tabulated Values
+-----------------------------------
+
+The function to calculate μ from tabulated values is located
+in the ``diffpy.utils.tools`` module. So first, import the function,
+
+.. code-block:: python
+
+   from diffpy.utils.tools import compute_mu_using_xraydb
+
+To calculate μ, you need to know the sample composition, and X-ray energy, and sample mass density (g/cm\ :sup:`3`).
+
+.. code-block:: python
+
+   composition = "Fe2O3"
+   energy_keV = 17.45 # Mo K-alpha energy
+   sample_mass_density = 5.24 # g/cm^3
+
+Now calculate μ using the ``compute_mu_using_xraydb`` function.
+
+.. code-block:: python
+
+   mu = compute_mu_using_xraydb(composition, energy_keV, sample_mass_density)
+   print(f"Calculated mu: {round(mu, 3)} mm^-1")
+
+This will output the calculated X-ray absorption coefficient, μ, in mm\ :sup:`-1`.
+
+.. code-block:: console
+
+   Calculated mu: 13.967 mm^-1

news/mu-ex.rst

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+**Added:**
+
+* Add examples for calculating absorption coefficient.
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>