I have a web application that reads the values of a few input fields (alphanumeric) and constructs a very simple xml that is passes to the server, using jQuery's $.ajax() method. The template for that xml is:

<request>
    <session>[some-string]</session>
    <space>[some-string]</space>
    <plot>[some-string]</plot>
    ...
</request>

Sending such requests to the server when the inputs contain Finnish diacritical characters (such as ä or ö) raises a problem in terms of character encoding with different browsers. For instance, if I add the word Käyttötarkoitus" in one of the inputs, here's how Chrome and Firefox send EXACTLY the same request to the server:

Chrome:

<request>
    <session>{string-hidden}</session>
    <space>2080874</space>
    <plot>Käyttötarkoitus</plot>
    ...
</request>

FF 12.0:

<request>
    <session>{string-hidden}</session>
    <space>2080874</space>
    <plot>Käyttötarkoitus</plot>
    ...
</request>

And here is the code fragment that I use to send the requests:

$.ajax({ 
    type: "POST", 
    url: url,
    dataType: 'xml;charset=UTF-8',
    data: xml, 
    success: function(xml) { 
        //
    },
    error: function(jqXHR, textStatus, errorThrown) {
        //
    }
});

Why do I get different encodings and how do I get rid of this difference? I need to fix this problem because it's causing other on the server-side.