Is this type of action considered deflamation

I was fired from my job in Aug. 2009, after being falsely accused of falsifying vehicle mileage reports. I have substantial proof my former employer is not being truthful (statement from accounts visited that day, sales notes entered into the computer, and recipts for expenses that were reimbursed). The proof my former employer used is just their hand written notes (which are not truthful). Needless to say, because of this termination, I cannot find another job, because when future employers see (on applications)or hear that I've been terminated, I am not hired or a candidate for the job any longer. I have never in my almost 40 year career been accused of dishonesty, or ever been fired. Isn't this deflamation of character, and do I have a possible case against them.