Email notification for custom RTC role

Hi,

I am looking for some materials/link which can help me trigger email notifications when a team member is assigned to a custom role.

Example: I have a new Change Request work item type and I have included a new Change Impact Assessor role. I want an email to be sent out to the person selected in this role(from the WI form). It should work similar to the "Owned By" Field.

Thanks for any assistance.

Naweed