Added a reference for the ESIS grating design.

docs/refs.bib

@@ -40,4 +40,18 @@ @inproceedings{Rebellato2018
 doi = {10.1117/12.2313346},
 URL = {https://doi.org/10.1117/12.2313346}
 }
-
+@article{Soufli2012,
+    author = {Soufli, Regina and Fernández-Perea, Mónica and Baker, Sherry L. and Robinson, Jeff C. and Alameda, Jennifer and Walton, Christopher C.},
+    title = "{Spontaneously intermixed Al-Mg barriers enable corrosion-resistant Mg/SiC multilayer coatings}",
+    journal = {Applied Physics Letters},
+    volume = {101},
+    number = {4},
+    pages = {043111},
+    year = {2012},
+    month = {07},
+    abstract = "{Magnesium/silicon carbide (Mg/SiC) has the potential to be the best-performing reflective multilayer coating in the 25–80 nm wavelength region but suffers from Mg-related corrosion, an insidious problem which completely degrades reflectance. We have elucidated the origins and mechanisms of corrosion propagation within Mg/SiC multilayers. Based on our findings, we have demonstrated an efficient and simple-to-implement corrosion barrier for Mg/SiC multilayers. The barrier consists of nanometer-scale Mg and Al layers that intermix spontaneously to form a partially amorphous Al-Mg layer and is shown to prevent atmospheric corrosion while maintaining the unique combination of favorable Mg/SiC reflective properties.}",
+    issn = {0003-6951},
+    doi = {10.1063/1.4737649},
+    url = {https://doi.org/10.1063/1.4737649},
+    eprint = {https://pubs.aip.org/aip/apl/article-pdf/doi/10.1063/1.4737649/14265083/043111\_1\_online.pdf},
+}

esis/flights/f1/optics/gratings/materials/_materials.py

@@ -17,6 +17,7 @@
 def multilayer_design() -> optika.materials.MultilayerMirror:
     """
     The as-designed multilayer coating for the ESIS diffraction gratings.
+    This coating is based on the design outlined in :cite:t:`Soufli2012`.
 
     Based on the analysis of :cite:t:`Rebellato2018`, this model uses
     :cite:t:`Kortright1988` for the silicon carbide optical constants, and