pen: add ad-hoc emission data points below 375 nm

src/legendoptics/data/pen_wlscomponent.dat

@@ -1,4 +1,11 @@
 # nm       dimensionless
+
+# ad-hoc data points added by legend-pygeom-optics
+358.000000 0.000000
+365.000000 0.000080
+370.000000 0.000297
+
+# from here on data from [Leonhardt2024]_
 375.016000 0.000594
 375.808000 0.000690
 376.600000 0.000767

src/legendoptics/pen.py

@@ -69,9 +69,13 @@ def pen_wls_emission() -> tuple[Quantity, Quantity]:
     """WLS Emission spectrum.
 
     [Leonhardt2024]_ measure the emission spectrum of a PEN sample made from the same pellets as
-    in LEGEMD-200 sample at an excitation wavelength of 128nm and at 87K, so exactly in our
+    in LEGEND-200 sample at an excitation wavelength of 128nm and at 87K, so exactly in our
     experimental conditions.
 
+    .. note::
+        Data points below 375 nm are an ad-hoc continuation of the measured data to zero, avoiding
+        a steep step. They are not based on actual measurements.
+
     .. optics-plot::
     """
     return readdatafile("pen_wlscomponent.dat")
@@ -97,7 +101,6 @@ def pen_wls_absorption() -> tuple[Quantity, Quantity]:
         For geometries with thick PEN objects, the absorption length should not matter too much—in a
         certain range, all light will be absorbed anyway.
 
-
     The absorbing range and approximate magnitude have been extracted from [Ouchi2006]_, figure 1.
 
     .. optics-plot:: {'yscale': 'log'}