multi-line text and {\"a} in formulas

[Reinhard Borek]

Hi,
how I can write multi-line text and chars like {\"a} in formulas?
When I try to put 'ä' in text mode in a formula, it does not occur
anything. When I try to put {\"a} in LaTex-mode in a formula, it does
not work. 

greetings, Reinhard
-- 
[EMAIL PROTECTED]
Reinhard Borek
Exp. Phys I
Fachbereich Physik
Martin-Luther-Universität Halle-Wittenberg
Friedemann-Bach-Platz 6
06108 Halle/Saale