Two‐Photon Excitation Spectra of Trivalent Rare‐Earth Ion Luminescence in Crystals

Abstract

Theoretical and experimental investigations are made of two-photon absorption spectra of trivalent rare-earth ions in crystals. Effective cross-sections, selection rules, and relative intensities of the components are found. The most intensive two-photon transitions are established. Two-photon excitation spectra of luminescence of Er3+ and Ho3+ ions in CaF, are obtained and effective excitation cross-sections are measured using a tunable dye laser (715 to 850 nm). It is shown that the spectra have a peculiar structure which differs considerably from that of the one-photon absorption spectra. The experimental results agree with theory. It is established that one of the levels in Hos+ is the level 5G, rather than sK, usually assumed.

Sum rules for multi-photon spectroscopy of ions in finite symmetry

“…A word should be said about previous works on this subject. The subject treated in the present Letter has been touched upon in [13,21,[23][24][25][26] for p = 2 and fully developed in the thesis by one of the authors (M.D.) for p arbitrary.…”

“…In the case of one-photon transitions (p = 1) within the configuration nℓ N , (20) with k S = 0 gives as a special case the operator implicitly considered by several people in order to explain intra-configurational one-photon transitions for d N [1,2] or f N [3,4] ions in crystals. In the case of inter-configurational two-photon transitions (p = 2) between the configuration nℓ N and the configuration nℓ N−1 n ′ ℓ ′ with ℓ + ℓ ′ odd, (20) with k S = 0 yields as particular cases the operators introduced in connection with either a static coupling mechanism [13,16,19,22,24] when X (t) is the odd crystal-field tensor or a dynamic coupling mechanism [19,22] when X (t) is the ligand polarization tensor.…”

“…Equation ( 20) unifies various models introduced in [1][2][3][4] for p = 1 and in [5,[13][14][15][16][17][18][19][20][21][22][23][24] for p = 2.…”

Two-photon spectroscopy of transition metal ions in cubical symmetry

“…correspond to the standard second-order mechanisms [1][2][3][4] and to the so-called thirdorder mechanisms (which may take into account ligand, crystal-field and spin-orbit effects) [5][6][7][8][9], respectively.…”

“…With the availability of tunable dye lasers, two-photon spectroscopy of transition ions in molecular or solid-state environments (generic symmetry G) has been the object of numerous developments both from an experimental and theoretical viewpoint . Indeed, two-photon spectroscopy turns out to be a useful complement to one-photon spectroscopy because it allows levels to be reached which cannot be seen in one-photon spectroscopy [1][2][3][4][5][6][7][8][9][10][11][12][13]. There are now many two-photon absorption spectra published for rare-earth ions (generic configuration 4f N for the lanthanides or 5f N for the actinides) in various surroundings.…”