Shaping negative pulses to positive ones
You say that you have tried this circuit:



but that the output is stuck at Vcc.  You didn't say what opamp you are using, but most opamps should be able to handle this.  They certainly should not produce Vcc with nothing connected.

One possibility is that you have the inputs flipped.  Start by debugging the case where the input is tied to ground.  The output should be very close to ground.  Until you get that, there is no point trying to feed pulses to it.

You also need to consider the impedance of the source.  Your inverting amplifies has a 10 k&Omega; input impedance.  If the source impedance is not significantly lower than that, then the signal will get attenuated.  It doesn't seem like you need unusually high speed, so you should be able to use about 10x higher resistors.  In other words, 100 k&Omega; and 800 k&Omega; if you still want a gain of -8.

Added

Many opamps can do what you asked, but not the one you picked.  Now that you have supplied a link to the opamp datasheet, the problem is clear.  The common mode input voltage range needs over 4 V headroom from the negative supply.  You are trying to operate the amp with the inputs at the negative supply.  That's clearly well out of spec.

To fix this, use a more appropriate opamp, or give it a negative supply of -5 V or lower.  This is, of course, after properly reading the datasheet.