Get content of single by slug
I don't think that either the single's uri or the handle is technically considered a slug per se, although in the case of singles craft likely interprets the handle as such. A more appropriate way to access a single would be by using its section handle.

(updated) 

{% if craft.request.getSegment(1) == "this-is-a-segment" %}
    {% set item = craft.entries.section('mySectionHandle').first() %}
{% endif %}