Exponential frames for unbounded sets
  For every set $S$ of finite measure in $\mathbb{R}$ we construct a discrete set of real frequencies $\Lambda$ such that the exponential system $\{\exp(i\lambda t),\lambda\in\Lambda\}$ is a frame in $L^2(S)$ 
Shahaf Nitzan, Alexander Olevskii and Alexander Ulanovskii
math.CA