Projection exposure method and projection exposure system

In a primary radiation projection exposure method, having a central wavelength λ is generated and is guided along a path illuminated by the illumination system and a projection along a path through the projection system. The center wavelength within the wavelength range Δλ changes, the wavelength range Δλ λ MIN≤λ having a lower limit and an upper limit λ MAX> λ. At least one gas absorbent specific absorption coefficient k (λ) between a minimum and a maximum absorption coefficient k MIN absorption coefficient k MAX changes, so that the absorption ratio (k MAX / k MIN) exceeds 10, the at least one gas from the absorber comprising oxygen (O 2), ozone group (O 3) and water vapor (H 2O) selected, but also in the illumination path along a projection path and at least one of the at least one gas-filled space. Concentration of the absorbent in the gas-filled space is controlled such that the absorbent material is kept below a predetermined threshold for all the change in absorbance of the total absorbance changes along different ray paths toward the image rays caused by the traveling field.