[en] This paper describes the determination of the molecular deuterium particle flux Γ_M by means of Fulcher-α-band spectroscopy. As previous investigations have shown , the measurement of the molecular flux is essential for an accurate determination of the total deuterium flux released from carbon plasma-facing components. Experiments have been carried out to ascertain the number of deuterium molecules released from a test limiter in the plasma edge of TEXTOR. For different plasma conditions, a molecular flux up to Γ_M≅5x10²⁰ s^-1 was measured. Fulcher-α-band spectroscopy is introduced as a straightforward method for the determination of Γ_M. We describe photon flux measurements, a comparison with Eirene calculations, and finally the determination of recycling particle fluxes. The conversion factor D/XB taken from a collisional-radiative model (CRMOL) and relating the number of molecular losses per photon was verified in gas injection experiments