XElement.GetNamespaceOfPrefix gets the namespace associated with a particular prefix for this XElement.
Imports <xmlns:aw="http://www.domain.com">
Module Module1
Sub Main()
Dim xmlTree As XElement = <aw:Root/>
Dim awNamespace As XNamespace = GetXmlNamespace(aw)
Console.WriteLine("Namespace: {0}", awNamespace)
End Sub
End Module