Probability distribution of first arrival time in Poisson Process

[phyalan]

According to wiki:
http://en.wikipedia.org/wiki/Poisson_process

The probability for the waiting time to observe first arrival in a Poisson process P(T1>t)=exp(-lambda*t)
But what is the Probability Distribution P(T1=t) of the waiting time itself? How to calculate that?

 

[mathman]

Since the waiting time has a continuous distribution, the probability of T1 having a particular value = 0. I suppose you would want the density function, λe^-λt.