Femtosecond filamentation induced fluorescence technique for atmospheric sensing*
Yuan Shuaia),b),c), Chin See Leangc), Zeng He-Pinga),b),†
Fig.#cod#x00A0;7. Fluorescence spectra from the plasma grating induced by two interfering UV pulses blue curve, from plasma grating with a Bragg incident infrared pulses 800#cod#x00A0;nm10#cod#x00A0;mJ40#cod#x00A0;fs delayed 3.6#cod#x00A0;ps with respect to the UV pulses grey curve, and from plasma grating with two Bragg incident infrared pulses 800#cod#x00A0;nm10#cod#x00A0;mJ40#cod#x00A0;fs of 5#cod#x00A0;mJ subsequently delayed 3.6 and 7.2#cod#x00A0;ps with respect to the UV pulses green curve, respectively. The emission wavelengths were marked above the corresponding peaks for atomic ions and highly ionized ions. A dramatic increase of plasma and ionic fluorescence indicated impact ionization induced by the infrared pulses in the pre-formed plasma channels.