C# Split string on 'þ', not on 'th'

Question

In C# I have a string that I need to split on the character 'þ'. The problem is that the string is split on 'th' as well.

string dataline = 'is thisþis that';
string[] dataFields;
dataFields = dataline.Split('þ');

This will result in the output

'is '
'is'
'is '
'at'

What I want is

'is this'
'is that'

Is there a way to do this?