Mastering XRR Fitting

A free book on fitting an X-ray reflectivity (XRR) curve, from reading the raw curve to reporting the fit. It is written for a graduate student or engineer who has an XRR curve and has never fitted one, and it is built around one program, X-Ray Calc 3. Every step is something you do in that program.

Read it online: https://oleksiypenkov.github.io/MasteringXRR/

Download the PDF: Mastering-XRR-Fitting.pdf (the latest release; earlier editions are on the Releases page)

The book is written for X-Ray Calc 3.9.4. Its fitting method is the laboratory procedure described in Penkov, Peng & Fu, Teaching an LLM agent to fit XRR curves with X-Ray Calc 3, arXiv:2609.28926; the procedure and its data are deposited at doi:10.5281/zenodo.22851595.

How to cite

Penkov, O. (2026). Mastering XRR Fitting: Fitting X-Ray Reflectivity Curves with X-Ray Calc 3. https://doi.org/10.5281/zenodo.22959661

This DOI always resolves to the latest edition. To cite one edition (for a page or figure number), use that version's DOI from the Zenodo record.

What is in this repository

• src/content/chapters/: the chapters, one MDX file each. This is the only source of the text.
• src/components/, src/layouts/, src/lib/: the site (Astro, with KaTeX for the equations) and the few calculations it shows, with their unit tests.
• public/figures/: the figures as the book shows them. figures-src/ holds the data behind them, and scripts/figures/ the scripts that computed and drew them.
• pdf-build/: the print edition, rendered from the running site.

Build the web edition

Node 20.19 or newer.

npm ci
npm run dev          # http://localhost:4331/MasteringXRR/
npm test             # unit tests
npm run build        # static site in dist/
npm run check:links  # every internal link and #fragment in dist/

Build the PDF

With npm run preview running (Python 3 with PyMuPDF, pypdf and BeautifulSoup, and a Playwright Chromium):

npm run pdf:render
npm run pdf:assemble
npm run pdf:verify

pdf-build/README.md describes the stages and the checks.

Rerun the figure scripts

The scripts in scripts/figures/ call the command-line server that ships with X-Ray Calc 3 and read the measured curves from the procedure's Zenodo deposit. Tell them where these are, either with environment variables or with a local-paths.json at the repository root (not committed):

{
  "XRC_MCP_EXE": "C:/path/to/a/copy/of/X-Ray Calc 3/XRC_MCP.exe",
  "XRC_DEPLOY": "C:/path/to/X-Ray Calc 3",
  "XRR_DEPOSIT": "C:/path/to/the/unzipped/deposit"
}

scripts/figures/local_paths.py lists every key. The outputs the book uses are already in figures-src/ and public/figures/, so the site builds without any of this.

Licence

The text, figures and data are under CC BY 4.0; the code is under the MIT licence.