Scattered states and bound states ?

[hiphys]

Hello,I'm physics student.I'm from Vietnam and my English is not very good.
I was wondering if anyone could help me out with a question : what are scattered states and bound states ?
I'm interested in "Temperature-dependent Coulomb interation in hydrogenic systems".
In this topic,the effective pair potential is defined as afunction of the two-particle radial distribution function (rdf).
When particles have charges of opposite sign,their rdf can be considered as a sum of two terms : the contributions from scattered states and bound states .
I 've looked up those in many books,but I haven't found the answer.Please help me.Thanks.

[turin]

I don't know what the topic means by that, but a scattered state is one that is influenced by a scattering potential but has nontrivial |ψ|2 at r -> infinity, and a bound state is one that has |ψ|2 -> 0 at r -> infinity.

[Anglea]

I don't know what the topic means by that, but a scattered state is one that is influenced by a scattering potential but has nontrivial |ψ|2 at r -> infinity, and a bound state is one that has |ψ|2 -> 0 at r -> infinity.
I s this means that the bound state is localized and normalized, and the scattered state is not?if so why is that as I think it is the opposite as the bound state usually given by exponential function and ,e.g bound particle always have an exponential wave function?so this means is not narmalised, please show me where is my confusion