eva_1996
========

E\. Eva and K\. Mann, Appl\. Phys\. A 62, 143 \(1996\)

`Source record <https://github.com/LupoLab/optmat/blob/main/src/optmat/data/sources/eva_1996.toml>`__ · :doc:`Catalogue </the-data/sources>` · :doc:`Review register </register>`

DOI: `10\.1007/bf01575711 <https://doi.org/10.1007/bf01575711>`__

**Source kind:** measurement

**Recorded technique:** Laser calorimetry\: 25 ns excimer pulses \(Lambda Physik EMG202\) at 351, 248 or 193 nm, apertured and focused to a point behind the slightly tilted sample; transmitted energy by a pyroelectric detector \(Ophir PE50\), incident energy computed from the refractive index and the absorbed energy; temperature by two NTC resistors, calibrated electrically with a resistor glued at the laser spot\. Irradiation 30 s at 19\-150 Hz, energy density H set by a variable attenuator, intensities 2\-80 MW/cm2 \(1/e^2 maximum 80 MW/cm2\)\. Beam profile a flat Gaussian \(intensity at 90 % of the maximum twice that at 1/e^2\), at most 6 x 4 mm2 on 25 mm samples\.

**Materials in structured entries:** BaF2, CaF2, LiF, MgF2, SiO2, SiO2\_quartz

**Dataset quantities:** absorption\_coefficient, band\_gap, two\_photon\_absorption\_coefficient

**Contents:** 25 datasets; 1 formula.

Curation notes
--------------

Table 1 \(p\. 4\) is transcribed in full\. It is a wide table with a label column \('351 nm\:', '248 nm\:', '193 nm\:'\) before each wavelength block; checked against the image row by row \(see the extraction script\)\: every value is in its column\. Caption \(verbatim\)\: 'Absolute absorption coefficients of commercially available UV\-grade substrates at 351, 248 and 193 nm \(3\.5/5/6\.4 eV\) \(surface absorption not accounted for\), absolute uncertainty is \+\-20 % for alpha and \+\-40 % for beta; beta\_Lit\. \(measured at 248 nm / 0\.7 ps\) and E\_gap from \[2\] unless stated otherwise'\. Ref\. \[2\] is taylor\_1988, \[19\] brimacombe\_1989, \[20\] weinberg\_1979\. '\-' is 'not measured'\.

Definitions \(p\. 1\)\: dI/dz = \-alpha I \- beta I^2 \(Eq\. 1\), and the absorptance of a sample of thickness dz is A = dz \(alpha \+ beta H / tau\_pulse\) \(Eq\. 2\)\: alpha from the offset and beta from the slope of A against intensity, so alpha is a Napierian \(base e\) coefficient per length\. A is the absorbed over the incident energy \(Eq\. 3\); the incident energy inside the sample is computed with the refractive index, so front\- surface reflection is removed, but surface absorption is included in alpha\. For a flat\-topped profile beta is the slope; for this beam 'a constant factor of 0\.7 applies' \(p\. 2, stated for BaF2, from attenuation computed over ten areas of homogeneous intensity\); whether it was applied to the other materials is not said\.

Samples and grades\: fused silica S1 and S2 are Suprasil 1 and Suprasil 2 \(Heraeus; p\. 2 and p\. 5\: Suprasil 2 'differs from Suprasil 1 only in optical homogeneity'; both high\-OH\)\. 'A CaF2 crystal \(Korth Kristalle\)' is named in Sec\. 3\.1 without saying which CaF2 row it is\. The crystalline quartz is z\-cut \(p\. 6\)\: light along the optic axis, so its datasets are given axis 'o' \(an inference from the cut\)\. No other orientation is stated \(MgF2's is not\)\. Liquids\: none\.

Thicknesses dz \(mm\) as printed\: S1 1, CaF2 2 and 5 \(two rows\), LiF 2, MgF2 2, S2 2, quartz 2, BaF2 5, CaF2 5 \(the 193 nm row\); kept in the files' printed column\.

Text values \(not tabulated\)\: BaF2 at 248 nm, maximum absorptivity 2\.1 % at 1\.1 J/cm2, transmission loss \(2 \+\- 0\.8\) %; linear fits for two samples consistent to \+\-6 % relative \(p\. 2\); up to 24 % of the BaF2 slope may be intensity\-dependent colour\-centre absorption \(transient, lifetime tau\_life = 50 ms in the model of Eq\. 4\), 'then our value for beta must be too large' \(p\. 3\)\. Suprasil 1 at 248 nm, 1\.4 J/cm2, saturates at alpha = 0\.14/cm after 3e5 pulses \(induced absorption, not an intrinsic value; p\. 4\)\. The fused\-silica beta comes from absorptance extrapolated to zero pulses \(Figs\. 6\-7\); 'some of the slope \(up to a third\) might be due to transient, intensity\-dependent color\-center formation' \(p\. 5\)\. CaF2 at 193 nm\: 'as the sample was damaged at 420 mJ/cm2 already, only approximate coefficients could be derived' \(p\. 3\); the authors conclude from the absence of two\-photon absorption at 248 nm that the CaF2 gap exceeds 2 x 5\.0 eV\.

Formula\: the degradation\-rate fit of Suprasil 2 at 248 nm \(below\)\. The figures \(2\-10\) are not digitised\: absorptance against H or pulse number for CaF2 and MgF2 \(Fig\. 2\), BaF2 \(Figs\. 3\-4\), Suprasil 1 and 2 \(Figs\. 5\-9\) and quartz \(Fig\. 10\)\.

Reproductions\: the E\_gap column and the beta\_Lit values come from taylor\_1988 \(the CaF2 \.08 is Taylor's 8\.3e\-12 rounded; LiF and MgF2 '\<= \.01' are Taylor's \<= 1\.3e\-12 bounds rounded\), 2\.1 from brimacombe\_1989 \(its 248 nm fibre value, 2\.1e\-4 cm/MW = 2\.1e\-10 cm/W, measured with 9 ns pulses although the caption says 0\.7 ps\), and the quartz gap from weinberg\_1979\.

**Recorded bibliographic identity status:** VALIDATED\_WITH\_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.

Datasets
--------

eva\_1996/band\_gap\_SiO2
~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "band_gap_SiO2",
     "material": "SiO2",
     "file": "SiO2/eva_1996__band_gap_SiO2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "band_gap",
     "unit": "eV",
     "abscissa": "none",
     "use": "reproduced",
     "reproduced_from": [
       "taylor_1988"
     ],
     "parameters": {
       "kind": "not stated"
     }
   }

E\_gap from Ref\. \[2\] \(taylor\_1988\), per the caption\. Printed on rows 1 and 6\.

eva\_1996/band\_gap\_CaF2
~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "band_gap_CaF2",
     "material": "CaF2",
     "file": "CaF2/eva_1996__band_gap_CaF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "band_gap",
     "unit": "eV",
     "abscissa": "none",
     "use": "reproduced",
     "reproduced_from": [
       "taylor_1988"
     ],
     "parameters": {
       "kind": "not stated"
     }
   }

E\_gap from Ref\. \[2\] \(taylor\_1988\), per the caption\. Printed on rows 2, 3 and 9\.

eva\_1996/band\_gap\_LiF
~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "band_gap_LiF",
     "material": "LiF",
     "file": "LiF/eva_1996__band_gap_LiF.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "band_gap",
     "unit": "eV",
     "abscissa": "none",
     "use": "reproduced",
     "reproduced_from": [
       "taylor_1988"
     ],
     "parameters": {
       "kind": "not stated"
     }
   }

E\_gap from Ref\. \[2\] \(taylor\_1988\), per the caption\.

eva\_1996/band\_gap\_MgF2
~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "band_gap_MgF2",
     "material": "MgF2",
     "file": "MgF2/eva_1996__band_gap_MgF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "band_gap",
     "unit": "eV",
     "abscissa": "none",
     "use": "reproduced",
     "reproduced_from": [
       "taylor_1988"
     ],
     "parameters": {
       "kind": "not stated"
     }
   }

E\_gap from Ref\. \[2\] \(taylor\_1988\), per the caption\.

eva\_1996/band\_gap\_BaF2
~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "band_gap_BaF2",
     "material": "BaF2",
     "file": "BaF2/eva_1996__band_gap_BaF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "band_gap",
     "unit": "eV",
     "abscissa": "none",
     "use": "reproduced",
     "reproduced_from": [
       "taylor_1988"
     ],
     "parameters": {
       "kind": "not stated"
     }
   }

E\_gap from Ref\. \[2\] \(taylor\_1988\), per the caption\.

eva\_1996/band\_gap\_SiO2\_quartz
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "band_gap_SiO2_quartz",
     "material": "SiO2_quartz",
     "file": "SiO2_quartz/eva_1996__band_gap_SiO2_quartz.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "band_gap",
     "unit": "eV",
     "abscissa": "none",
     "use": "reproduced",
     "reproduced_from": [
       "weinberg_1979"
     ],
     "parameters": {
       "kind": "not stated"
     }
   }

Printed '≈ 9 \[20\]' \(approximate\)\. weinberg\_1979 deduces 9\.3 eV for amorphous thermally grown SiO2 from the field dependence of photoconductivity and reviews ~9 eV estimates \(among them a 9\.2 eV indirect gap calculated for alpha\-quartz\); it prints no measured gap of crystalline quartz, so the attribution is loose\.

eva\_1996/alpha\_SiO2\_suprasil1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "alpha_SiO2_suprasil1",
     "material": "SiO2",
     "file": "SiO2/eva_1996__alpha_SiO2_suprasil1.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "absorption_coefficient",
     "unit": "cm-1",
     "scale": 0.001,
     "abscissa_unit": "nm",
     "use": "primary",
     "uncertainty": {
       "relative": 0.2,
       "level": "not stated"
     },
     "parameters": {
       "base": "e",
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000,
       "grade": "Suprasil 1"
     }
   }

From the offset of absorptance against intensity \(Eq\. 2\); surface absorption not accounted for\. 1 mm sample; 351 nm only \(no two\-photon absorption at 351 nm\)\.

eva\_1996/alpha\_SiO2\_suprasil2
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "alpha_SiO2_suprasil2",
     "material": "SiO2",
     "file": "SiO2/eva_1996__alpha_SiO2_suprasil2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "absorption_coefficient",
     "unit": "cm-1",
     "scale": 0.001,
     "abscissa_unit": "nm",
     "use": "primary",
     "uncertainty": {
       "relative": 0.2,
       "level": "not stated"
     },
     "parameters": {
       "base": "e",
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000,
       "grade": "Suprasil 2"
     }
   }

From the offset of absorptance against intensity \(Eq\. 2\); surface absorption not accounted for\. 2 mm; at 248 nm extrapolated to zero pulses \(Figs\. 6\-7\)\. The 193 nm value is printed '≈ 30' \(approximate; Fig\. 9 shows it rising with pulse number\)\.

eva\_1996/alpha\_CaF2
~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "alpha_CaF2",
     "material": "CaF2",
     "file": "CaF2/eva_1996__alpha_CaF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "absorption_coefficient",
     "unit": "cm-1",
     "scale": 0.001,
     "abscissa_unit": "nm",
     "use": "primary",
     "uncertainty": {
       "relative": 0.2,
       "level": "not stated"
     },
     "parameters": {
       "base": "e",
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000
     }
   }

From the offset of absorptance against intensity \(Eq\. 2\); surface absorption not accounted for\. Three rows\: 2 mm at 351 nm, 5 mm at 248 nm, 5 mm at 193 nm \(the last row; the sample was damaged at 420 mJ/cm2 and the 193 nm values are 'approximate', p\. 3\)\.

eva\_1996/alpha\_LiF
~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "alpha_LiF",
     "material": "LiF",
     "file": "LiF/eva_1996__alpha_LiF.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "absorption_coefficient",
     "unit": "cm-1",
     "scale": 0.001,
     "abscissa_unit": "nm",
     "use": "primary",
     "uncertainty": {
       "relative": 0.2,
       "level": "not stated"
     },
     "parameters": {
       "base": "e",
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000
     }
   }

From the offset of absorptance against intensity \(Eq\. 2\); surface absorption not accounted for\. 2 mm\. The rise from 351 to 248 nm is ascribed to colour\-centre bands near 250 nm \(p\. 2\)\.

eva\_1996/alpha\_MgF2
~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "alpha_MgF2",
     "material": "MgF2",
     "file": "MgF2/eva_1996__alpha_MgF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "absorption_coefficient",
     "unit": "cm-1",
     "scale": 0.001,
     "abscissa_unit": "nm",
     "use": "primary",
     "uncertainty": {
       "relative": 0.2,
       "level": "not stated"
     },
     "parameters": {
       "base": "e",
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000
     }
   }

From the offset of absorptance against intensity \(Eq\. 2\); surface absorption not accounted for\. 2 mm; orientation not stated\.

eva\_1996/alpha\_SiO2\_quartz
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "alpha_SiO2_quartz",
     "material": "SiO2_quartz",
     "file": "SiO2_quartz/eva_1996__alpha_SiO2_quartz.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "absorption_coefficient",
     "unit": "cm-1",
     "scale": 0.001,
     "abscissa_unit": "nm",
     "use": "primary",
     "uncertainty": {
       "relative": 0.2,
       "level": "not stated"
     },
     "parameters": {
       "base": "e",
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000,
       "axis": "o"
     }
   }

From the offset of absorptance against intensity \(Eq\. 2\); surface absorption not accounted for\. z\-cut, 2 mm \(axis 'o' inferred from the cut\)\.

eva\_1996/alpha\_BaF2
~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "alpha_BaF2",
     "material": "BaF2",
     "file": "BaF2/eva_1996__alpha_BaF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "absorption_coefficient",
     "unit": "cm-1",
     "scale": 0.001,
     "abscissa_unit": "nm",
     "use": "primary",
     "uncertainty": {
       "relative": 0.2,
       "level": "not stated"
     },
     "parameters": {
       "base": "e",
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000
     }
   }

From the offset of absorptance against intensity \(Eq\. 2\); surface absorption not accounted for\. 5 mm; offset of the linear fit \(Fig\. 3\)\.

eva\_1996/beta\_SiO2\_suprasil2
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "beta_SiO2_suprasil2",
     "material": "SiO2",
     "file": "SiO2/eva_1996__beta_SiO2_suprasil2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "primary",
     "uncertainty": {
       "relative": 0.4,
       "level": "not stated"
     },
     "parameters": {
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000,
       "grade": "Suprasil 2"
     }
   }

Slope of absorptance against intensity \(Eq\. 2\)\. 2 mm; absorptance extrapolated to zero pulses \(Figs\. 6\-7\), eliminating the cumulative colour\-centre increase only; up to a third of the slope may be transient colour\-centre absorption \(p\. 5\)\.

eva\_1996/beta\_SiO2\_quartz
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "beta_SiO2_quartz",
     "material": "SiO2_quartz",
     "file": "SiO2_quartz/eva_1996__beta_SiO2_quartz.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "primary",
     "uncertainty": {
       "relative": 0.4,
       "level": "not stated"
     },
     "parameters": {
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000,
       "axis": "o"
     }
   }

Slope of absorptance against intensity \(Eq\. 2\)\. z\-cut, 2 mm \(axis 'o' inferred\); increase linear in H, virtually no degradation \(Fig\. 10\)\.

eva\_1996/beta\_BaF2
~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "beta_BaF2",
     "material": "BaF2",
     "file": "BaF2/eva_1996__beta_BaF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "primary",
     "uncertainty": {
       "relative": 0.4,
       "level": "not stated"
     },
     "parameters": {
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000
     }
   }

Slope of absorptance against intensity \(Eq\. 2\)\. 5 mm\. At 248 nm\: slope times the beam form factor 0\.7, reversible, up to 24 % possibly transient colour\-centre absorption \(p\. 3\)\. At 193 nm\: 'slightly smaller than at 248 nm'; surface damage after 35 000 pulses at 0\.9 J/cm2\.

eva\_1996/beta\_CaF2
~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "beta_CaF2",
     "material": "CaF2",
     "file": "CaF2/eva_1996__beta_CaF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "primary",
     "excluded_rows": {
       "3/248": "printed '≈ 0': no two-photon absorption detected (band gap above twice the photon energy), not a measured magnitude"
     },
     "uncertainty": {
       "relative": 0.4,
       "level": "not stated"
     },
     "parameters": {
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000
     }
   }

Slope of absorptance against intensity \(Eq\. 2\)\. 5 mm samples\. The 193 nm value is 'approximate' \(damage at 420 mJ/cm2, p\. 3\)\.

eva\_1996/beta\_LiF
~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "beta_LiF",
     "material": "LiF",
     "file": "LiF/eva_1996__beta_LiF.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "excluded",
     "uncertainty": {
       "relative": 0.4,
       "level": "not stated"
     },
     "parameters": {
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000
     }
   }

Slope of absorptance against intensity \(Eq\. 2\)\. 2 mm; printed '≈ 0'\: no two\-photon absorption detected \(band gap above twice the photon energy\), not a measured magnitude\.

eva\_1996/beta\_MgF2
~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "beta_MgF2",
     "material": "MgF2",
     "file": "MgF2/eva_1996__beta_MgF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "excluded",
     "uncertainty": {
       "relative": 0.4,
       "level": "not stated"
     },
     "parameters": {
       "form": "bulk",
       "technique": "calorimetry",
       "pulse_fs": 25000000
     }
   }

Slope of absorptance against intensity \(Eq\. 2\)\. 2 mm; printed '≈ 0'\: no two\-photon absorption detected \(band gap above twice the photon energy\), not a measured magnitude\.

eva\_1996/taylor\_248\_SiO2
~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "taylor_248_SiO2",
     "material": "SiO2",
     "file": "SiO2/eva_1996__taylor_248_SiO2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "reproduced",
     "reproduced_from": [
       "taylor_1988"
     ],
     "parameters": {
       "pulse_fs": 700
     }
   }

beta\_Lit\. column, 'measured at 248 nm / 0\.7 ps' \(caption\), from Ref\. \[2\] \(taylor\_1988\)\. Taylor's 4\.5e\-11 cm/W\.

eva\_1996/taylor\_248\_CaF2
~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "taylor_248_CaF2",
     "material": "CaF2",
     "file": "CaF2/eva_1996__taylor_248_CaF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "reproduced",
     "reproduced_from": [
       "taylor_1988"
     ],
     "parameters": {
       "pulse_fs": 700
     }
   }

beta\_Lit\. column, 'measured at 248 nm / 0\.7 ps' \(caption\), from Ref\. \[2\] \(taylor\_1988\)\. '\.08' is Taylor's 8\.3e\-12 cm/W rounded\.

eva\_1996/taylor\_248\_BaF2
~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "taylor_248_BaF2",
     "material": "BaF2",
     "file": "BaF2/eva_1996__taylor_248_BaF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "reproduced",
     "reproduced_from": [
       "taylor_1988"
     ],
     "parameters": {
       "pulse_fs": 700
     }
   }

beta\_Lit\. column, 'measured at 248 nm / 0\.7 ps' \(caption\), from Ref\. \[2\] \(taylor\_1988\)\. Taylor's 1\.1e\-10 cm/W\.

eva\_1996/taylor\_248\_LiF
~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "taylor_248_LiF",
     "material": "LiF",
     "file": "LiF/eva_1996__taylor_248_LiF.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "excluded",
     "reproduced_from": [
       "taylor_1988"
     ],
     "parameters": {
       "pulse_fs": 700
     }
   }

beta\_Lit\. column, 'measured at 248 nm / 0\.7 ps' \(caption\), from Ref\. \[2\] \(taylor\_1988\)\. Printed '≤ \.01'\: Taylor's upper bound \(\<= 1\.3e\-12\) rounded; not a measured beta\.

eva\_1996/taylor\_248\_MgF2
~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "taylor_248_MgF2",
     "material": "MgF2",
     "file": "MgF2/eva_1996__taylor_248_MgF2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "excluded",
     "reproduced_from": [
       "taylor_1988"
     ],
     "parameters": {
       "pulse_fs": 700
     }
   }

beta\_Lit\. column, 'measured at 248 nm / 0\.7 ps' \(caption\), from Ref\. \[2\] \(taylor\_1988\)\. Printed '≤ \.01'\: Taylor's upper bound \(\<= 1\.3e\-12\) rounded; not a measured beta\.

eva\_1996/brimacombe\_248\_SiO2
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "brimacombe_248_SiO2",
     "material": "SiO2",
     "file": "SiO2/eva_1996__brimacombe_248_SiO2.csv",
     "table": "tbl_48a4477a3382",
     "quantity": "two_photon_absorption_coefficient",
     "unit": "cm/W",
     "scale": 1e-10,
     "abscissa_unit": "nm",
     "use": "reproduced",
     "reproduced_from": [
       "brimacombe_1989"
     ],
     "parameters": {
       "form": "fibre",
       "pulse_fs": 9000000
     }
   }

The '\(2\.1 \[19\]\)' in the Suprasil 2 beta\_Lit cell \(split by the script\)\: brimacombe\_1989's fibre value at 248 nm \(2\.1e\-4 cm/MW\), measured with 9 ns pulses, not 0\.7 ps as the caption says of the column; the text calls it 'the value reported for fibers with 9 ns pulses' \(p\. 5\)\.

Formulas
--------

eva\_1996/degradation\_rate
~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "degradation_rate",
     "material": "SiO2",
     "equation": "Fig. 7 and p. 5",
     "printed": "Delta A / n = 0.056 ppm (H[J/cm^2])^3.14",
     "variable": "H: energy density per pulse in J/cm2; Delta A / n: initial absorptance increase per pulse, in ppm",
     "range": "Suprasil 2, 2 mm, 248 nm, 33 Hz; the four energy densities (>= 600 mJ/cm2) at which ageing took place",
     "coefficients": {
       "a": "0.056",
       "p": "3.14"
     },
     "check": "The paper's own prediction, 160 ppm after 200 000 pulses at 256 mJ/cm2 (p. 6), is reproduced: 0.056 x 0.256^3.14 x 2e5 = 155 ppm (checked 2026-09-26)."
   }

Log\-log regression of the initial degradation rates of Fig\. 6; 'given the uncertainty and scarcity of the data points, a quadratic relationship cannot be ruled out' \(p\. 5\)\. No change was seen at 250 mJ/cm2 over 200 000 pulses \(a threshold the fit does not describe\)\.

Corrections
-----------

No dataset errata are recorded in this source record.

Formula corrections, where recorded, appear with their formulas above. Curation notes may also discuss corrections or unresolved interpretation. Consult the :doc:`review register </register>` for the checks and decisions.