For the data loggers, we give conversion times rather than sampling rates. The spec for the ADC20 can be found here: http://www.picotech.com/precision-data-acquisition.html
It has a range of conversion times that can be selected and faster conversion times will reduce the resolution. The following conversion times are available: 660 ms, 340 ms, 180 ms, 100 ms, 60 ms.
For your application, it sounds as if you require an oscilloscope. Have a look at the 2200 range, or if you require higher resolution, the PicoScope 3224.
Hope this helps