1. I created file ("C:\Users\Alkor\Desktop\a3434.raw") on my desktop 
2. Tried to get the file name from the absolute path

Actual result:
C:\Users\Alkor>python
Python 2.7.3 (default, Apr 10 2012, 23:24:47) [MSC v.1500 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> print os.path.basename ("C:\Users\Alkor\Desktop\a3434.raw")
Desktop3434.raw

The same for ntpath module:
>>> import ntpath
>>> print ntpath.basename ("C:\Users\Alkor\Desktop\a3434.raw")
Desktop3434.raw

Expected result:
a3434.raw

Environment:
Windows 7 x64 SP1 Ultimate
python 2.7.3150 (64-bit)