# A little help

1. Jun 4, 2008

### carlo

Hi to everybody;

I wanted to ask: which is the factor of conversion from cm^{-1} to eV?

Thank you!

2. Jun 4, 2008

### ZapperZ

Staff Emeritus
I'll ask this first so that you know where to look. Do you have Ashcroft and Mermin's "Solid State Physics" text? It is listed in the table on the inside back cover of the book.

Zz.

3. Jun 4, 2008

not here

thanks

4. Jun 4, 2008

### pam

A number I use is that 1=1.932 keV-Angstroms.

5. Jun 4, 2008

### HallsofIvy

Staff Emeritus
It might help to give more information! Since "reciprocal of centimeter" and "electron volt" measure quite different things, I assume you are talking about a very specific application.

6. Jun 4, 2008

### ZapperZ

Staff Emeritus
In optical conductivity area of study, it is very common to talk in inverse length to signify a corresponding energy scale. This is because from experiment, the value of "k" (either crystal momentum, electronic momentum, or wave number) falls out naturally from measurement.

Zz.

7. Jun 4, 2008

### ZapperZ

Staff Emeritus
So if you look in Ashcroft and Mermin, the standard "conversion" here is

$1 eV = 8.065 \times 10^3 cm^{-1}$

Zz.

8. Jun 4, 2008

### pam

The AM number and mine differ by a factor 2pi.
That is because mine is for k=1/lambda, with k in cm^-1,
and AM is for p=2pi/lambda with p in cm^-1.
You have to decide whether you are using k or p.