Submitted by Amanda Reig / Ursinus College on Fri, 04/24/2015 - 13:53
My Notes

A series of JAVA applets of Tanbe-Sugano diagrams were developed by Prof. Robert Lancashire at the University of the West Indies.  These diagrams allow students to determine deltao/B values based on ratios of peak energies without the pain of rulers and drawing lines.  There are also features that allow a person to input values and automatically calculate certain parameters.  You can also quickly find values of delta_o and B for certain complexes via a drop-down menu on some of the pages (e.g. Cr3+ complexes).    

Learning Goals

Students will be able to interpret absorption spectra using the provided Tanabe-Sugano diagram applets.

Implementation Notes

I use these applets when teaching Tanabe-Sugano diagrams in my class and students get significant practice with the applets through homework assignments and a lab experiment.

Note that you cannot use Chrome (Firefox or Internet Explorer both work) and you will likely need to add the website to your "safe" list in your JAVA settings in order for the applets to work.

Creative Commons License
Attribution, Non-Commercial, Share Alike CC BY-NC-SA
Marion Cass / Carleton College


Have you accessed this site recently?  I am accustom to creating security acceptions to make Java applets run but I am unable to make this site run (and I am using Firefox).

Marion Cass

Sat, 05/13/2017 - 23:22 Permalink
Amanda Reig / Ursinus College

I just tried it now and could get it to work - but it is a pain.  I used firefox.  I added the website to my "exception" list.  (Start Menu -> JAVA -> Configure JAVA -> Security).  You then have to close and restart firefox in order for it to work.  

If you put this in as the "exception" site ( then from the applets page all the versions should work (

Tue, 05/30/2017 - 11:08 Permalink
Anthony L. Fernandez / Merrimack College

I have been trying to access this site with no luck. I have added the site to my exceptions list and I cannot get it to run. I have tried it on a Mac (Safari and Friefox) and on a Windows 10 machine (Microsoft Edge). Any thoughts?

Mon, 10/15/2018 - 14:49 Permalink
Amanda Reig / Ursinus College

I found a workaround!  In Chrome, you can download the CheerpJ Applet Runner extension:

Once you go to the page with the JAVA applets, in the top right corner of your web browser, click the “Extensions” button (shown by the red arrow below). Then select the “CheerpJ Applet Runner” under “Access Requested”, then click “Run Applets” and “Allow”. The applet should now appear!

Tue, 01/12/2021 - 18:13 Permalink
Robert Lancashire / UWI, Jamaica

Thanks to Prof Bob Hanson, the original Tanabe-Sugano applets have been transpiled to HTML5/JavaScript codes.


has links to the new pages a little bit further down the page. I retired in 2015 and only just noticing this discussion about not being able to run the JAVA applets. The conversions were done some years ago and we still use the Laboratory exercises based on preparation of some Cr(III) complexes as well as recording their spectra (in plastic cells) and attempting to calculate the position of the 3rd spin-allowed transition which is generally in the UV region and not seen (especially with plastic cells!!). see

Still an issue with having the 3 JavaScript displays showing simultaneously so at present spectra and structure are shown on the first page and once peaks are selected then that information can be passed to the TS diagram on a second page and the results predicted.

Hope this helps



Fri, 01/21/2022 - 09:22 Permalink