Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Is the imaginary part of the relative permittivity of Au positive or negative?

Please login with a confirmed email address before reporting spam

Hello everyone.

Here is another question about "models. woptics. scattering_nanosphere". In this model, the imaginary part of the relative permittivity of Au is negative, e.g. the complex dielectric constant is
-16.8177-1.0668*i,
when the frequency of incident beam is 424THz. The data was extracted from
P. B. Johnson and R. W. Christy, "Optical Constants of the Noble Metals," Phys. Rev. B, vol. 6, pp. 4370-4379, 1972.
I downloaded the paper and found that the complex dielectric constant was defined as
(n+k*i)^2.
When the frequency of incident beam is 1.76eV (corresponding to 424THz), n=0.13 and k=4.103. Then the complex dielectric constant should be
-16.8177+1.0668*i.
I also checked some other papers about the data. It seems that most metals have a positive imaginary part of the relative permittivity.

Please help me to check it.
Thank you very much.

0 Replies Last Post 17 apr 2016, 21:20 GMT-4
COMSOL Moderator

Hello 峰 程

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.