Stark Width Data for Tb II, Tb III and Tb IV Spectral Lines

Round 1

Reviewer 1 Report

In this paper the author presents spectral line broadenings of various Tb ions. Given the lack of such parameters for these species, it is evident that their contribution would be of great interest. 

Nevertheless, there is a problem with the calculation procedure: The expression used for the calculation, being applicable for many ionic species, especially those that are well described with the LS coupling model, is quite rough for Tb ions (with a good number of electrons f) 

I agree with the author, that given the complexity of the ionic species under study, a more precise theoretical treatment is practically unapproachable. However, for the calculations performed can be considered as a first approximation, the author should include explicit, and sufficiently explanatory, arguments to justify his claim that “Its accuracy is 30-50 per cent in average and it can be useful when, due to lack of the needed atomic data, like in the case of terbium ions, other, more accurate methods could not be adequately applied.” 

In the current form and without any type of empirical contrast, it is not clear whether there is a reliable relationship between the calculations and the possible experimental values ​​of the studied parameters.

Author Response

I am very grateful to reviewer for valuable comments. Here is my answer:

Reviewer:

The author should include explicit, and sufficiently explanatory, arguments to justify his claim that “Its accuracy is 30-50 per cent in average and it can be useful when, due to lack of the needed atomic  data, like in the case of terbium ions, other, more accurate methods could not be adequately applied.” 

In the current form and without any type of empirical contrast, it is not clear whether there is a reliable  relationship between the calculations and the possible experimental values ​​of the studied parameters.

Answer:

At the end of the section "The method of research", the sentence: "The accuracy of  $W$ is 30-50 per cent in average and the calculated value can be useful when, due to lack of the needed atomic data, like in the case of terbium ions, other, more accurate methods, could not be  adequately applied". 
is replaced by:

In the Ref. \cite{Di87} the accuracy of  this method was checked by comparison of calculated with experimental results for a number of lines of N III, O III, Si III, S III, Cl III, Ar III, C IV, Si IV, S IV and Ar IV. The average ratio of measured to calculated Stark widths was 1.04. An additional check was made with experimental values for  Ne III, Ar III, Kr III and Xe III and the difference of experimental and calculated values was within the limits of 21\%. In the case of Tb II, Tb III and Tb IV there is no other experimental or theoretical data for comparison so that such measurements will be very useful to test 
the accuracy of calculations.  Since these spectra are more complicated, we can
expect that the average difference could be worse, we assume within the limits of 50 per cent. For some particular lines these  differences could be higher. 

Reviewer 2 Report

In the paper entitled "Stark width data for Tb II, Tb III and Tb IV spectral lines", Milan Dimitrijevic presents new calculations for 62 Tb III lines from 5d-6pj(6,j)o transition array. This is actually an addition to previous works: M. S. Dimitrijevic, Obs. Skalnaté Pleso 50, 122-127 (2020) for 5 multiplets of Tb II and M. S. Dimitrijevic, University Thought 10, 72-77 (2020) for 26 transitions in Tb III. The present work is therefore an update of the corresponding databases. Calculations were performed by using the symplified modified semi-empirical method for temperatures from 5 000 to 80 000 K and electron density of 10^17 cm-3. The obtained results are used also to discuss the regularities within multiplets and a supermultiplet. In particular, the obtained data made it possible to check similarities within Tb III 5d8L-6pj(6,j)o supermultiplet and confirmed the fact that such similarities could be used for a rough estimate of the missing values.

As indicated by the author, it is not possible to compare data obtained here with other results, since experimental or theoretical data for Stark broadening of Tb III lines do not exist.

The author is a well-known specialist in the field. His expertise is highly recognized and his contribution to the calculation of Stark widths of spectral lines is very important.

The clever semi-empirical method was widely used by atomic physicists over the past three decades, and still encounters a great success in the community of spectroscopists, especially in connection with astrophysical applications (see for instance the nice recent paper by the author in the journal "Data": M. S. Dimitrijevic, Forty Years of the Applications of Stark Broadening Data Determined with the Modified Semiempirical Method 5, 73 (2020).

The topic is well introduced (spectral lines of rare earth elements and determination of their abundances in atmospheres of white dwarfs and stars of A spectral typ, such as the so-called chemically-peculiar stars, r-process-enhanced stars, ro Ap stars, Przybylski star, etc.). The paper is clearly written and contains useful information. Beyond the availability of data which interest for the abovementioned astrophysical applications and forthcoming ones is obvious, the presented results are also useful for the study of regularities of Stark widths.

I therefore strongly recommend the paper for publication in the journal "Data".

Corrections :

- p. 1: "my be of interest" -W "may be of interest".
 
- p. 1: "...[5] as well as for...".

- p. 2: something is missing in the last sentence of the introduction.

- p. 2: "Stark widths(FWHM)".

- p. 2: the following sentence: "...since for them the used method is valid and in some cases they are and 40000K if the validitycondition is satisfied." is difficult to understand. It seems that something is missing.

- p. 2: "...,for each of temperatures" -> "for each temperature" or "for all the temperatures".

- p. 2: "Jj coupling" -> "jj coupling".

- p. 3: legend of Table 1: "choose between "table" and "Table".

- p. 9, table 2: the second column is not T[K], but lambda (Angstroms). Then the "lambda=", and "Angtroms" can be removed from all the lines of the column.

- p. 9: "Angstrem" (two occurrences).

_p. 9: "wdths"..

Author Response

I am very grateful to reviewer for useful comments

Corrections :

- p. 1: "my be of interest" -W "may be of interest".

Corrected. Thanks
 
- p. 1: "...[5] as well as for...".

Corrected. Thanks

- p. 2: something is missing in the last sentence of the introduction.

It is reformulated and now it is:
So, besides the new calculations, we present here Stark broadening data 
for Tb II, Tb III and Tb IV spectral lines. 

- p. 2: "Stark widths(FWHM)".

Corrected. Thanks.

- p. 2: the following sentence: "...since for them the used method is valid and in some cases they are and 40000K if the validitycondition is satisfied." is difficult to understand. It seems that something is missing.

It is reformulated as:
"...since for these the used method is valid. In some cases calculations are made also for 40 000 K if the validity condition is satisfied."

- p. 2: "...,for each of temperatures" -> "for each temperature" or "for all the temperatures".

I put "for each of the temperatures" according to demand of reviewer 3

- p. 2: "Jj coupling" -> "jj coupling".

"Jj coupling" is valid notation

- p. 3: legend of Table 1: "choose between "table" and "Table".

"This table shows" is deleted following the demand of Reviwewer 3

- p. 9, table 2: the second column is not T[K], but lambda (Angstroms). Then the "lambda=", and "Angtroms" can be removed from all the lines of the column.

Corrected. Thanks

- p. 9: "Angstrem" (two occurrences).

Corrected. Thanks

_p. 9: "wdths"..

Corrected. Thanks

Reviewer 3 Report

This paper presents data in the tradition of the school of Konjevic and the author and should be published.

However, the presentation needs polishing. I did my best to improve the text (see attached file).

Column captions of Table 2 are wrong and must be changed.

It is somewhere problematic if there is only one author and in the text always "we have ..." is used.

Comments for author File: Comments.pdf

Author Response

I am greatfull to reviewer for very careful reading of the manuscript. All errors indicated on the annotated 
copy are corrected.

Reviewer 4 Report

The article contains the results of new Strak width calculations of selected TbIII lines in a comprehensive set together with the author's previous results for Tb II Tb III Tb IV. Astrophysicists modeling or analyzing stellar atmospheres will be interested in this type of data to determine the presence / concentration of Tb atoms and ions in the atmosphere.

My remarks:

Typos:
-line 13, "my" -> "may"
-line 40, "widths(FWHM)" -> "widths (FWHM)"
-line 46, "ts satisfied" -> "is satisfied"
-line 104, The author claims that "In Table 2 are presented Stark FWHM expressed both in angstrems and in angular frequency units for a temperature of 10 000 K and electron density of 10^17 cm^-3."
          While Table 2 does not include FWHM angular frequency units, this data should be complete.         

Others:
The obtained results were presented in the form of a series of numerical FWHM values obtained on a grid T and with a constant value of Ne = 10^17 cm^{- 3}, for the purposes of interpolation. This form is established 
by tradition, but a bit old-fashioned. It seems that in the present age of computer availability, a more compact and more useful form of presenting such results would be different. Namely, in formula (1) one could separate the plasma factor from the atomic factor by writing:
W = Ne (cm ^ -3) / T ^ {1/2} (K) * C(spectral line), (1)
where factor C(spectral line) = ...
Then one C value in the table would suffice.
This comment should be considered as general and optional to apply.

Author Response

I am very grateful to reviewer for useful remarks

Typos:
-line 13, "my" -> "may"

Corrected. Thanks

-line 40, "widths(FWHM)" -> "widths (FWHM)"

Corrected. Thanks

-line 46, "ts satisfied" -> "is satisfied"

Corrected. Thanks

-line 104, The author claims that "In Table 2 are presented Stark FWHM expressed both in angstrems and in angular frequency units for a temperature of 10 000 K and electron density of 10^17 cm^-3."
          While Table 2 does not include FWHM angular frequency units, this data should be complete. 
          
Corrected. Thanks

Others:
The obtained results were presented in the form of a series of numerical FWHM values obtained on a grid T and with a constant value of Ne = 10^17 cm^{- 3}, for the purposes of interpolation. This form is established 
by tradition, but a bit old-fashioned. It seems that in the present age of computer availability, a more compact and more useful form of presenting such results would be different. Namely, in formula (1) one could separate the plasma factor from the atomic factor by writing:
W = Ne (cm ^ -3) / T ^ {1/2} (K) * C(spectral line), (1)
where factor C(spectral line) = ...
Then one C value in the table would suffice.
This comment should be considered as general and optional to apply.

I prefere to use "old-fashioned" standard  presentation, since this is the way how are presented data in VAMDC (Virtual Atomic and Molecular Data Center) and STARK-B database where these data will be included in the future. 

Round 2

Reviewer 1 Report

It is true that the result has been accurate in a series of species cited by the author. But none of them is a  rareearth with uncompleted f-layers.
There are no direct or indirect elements to contrast the results and they could be incorrect.
It is possible that it can always be argued that it is a first approximation. But it is certainly very crude.

But, that´s something.

Author Response

Thanks for your work!

Reviewer 2 Report

The author has made all the required corrections, the paper can be published.

I just noticed one remaining typographical error: the unit of lambda (Angstroms) is missing in the header of table 2.

Author Response

Thanks for your work!