Optics and Interferometry with ${\mathrm{Na}}_2$ Molecules

We have produced an intense, pure beam of sodium molecules ( ${\mathrm{Na}}_2$) by using light forces to separate the atomic and molecular species in a seeded supersonic beam. We used diffraction from a microfabricated grating to study the atomic and molecular sodium in the beam. Using three of these gratings, we constructed a molecule interferometer with fully separated beams and high contrast fringes. We measured both the real and imaginary parts of the index of refraction of neon gas for ${\mathrm{Na}}_2$ molecule de Broglie waves by inserting a gas cell in one arm of the interferometer.