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Elementary Processes of Excited Molecules and Atoms in Plasma
Published in Alexander Fridman, Lawrence A. Kennedy, Plasma Physics and Engineering, 2021
Alexander Fridman, Lawrence A. Kennedy
To determine which excited states are metastable and which can be easily deactivated by dipole radiation, it is convenient to use the selection rules. Actually, these rules indicate whether an electric dipole transition (and hence radiation emission or absorption) is allowed or forbidden. The selection rules allowing the dipole radiation in the case of L-S coupling are:The parity must change. Thus, as seen from Table 3.1, ground states and first resonance excited states have different parity.The multiplicity must remain unchanged. This rule can also be observed from Table 3.1, where spin-orbit interaction is predominant, resulting not in L-S but j-j coupling. Note that this rule cannot be applied to noble gases.Quantum numbers J and L must change by +1, −1 or 0 (however transitions 0→0 are forbidden). It can also be seen in the correspondence between the ground and the first resonance excited states presented in Table 3.1.
The Theory of Atom of Hydrogen
Published in Mikhail G. Brik, Chong-Geng Ma, Theoretical Spectroscopy of Transition Metal and Rare Earth Ions, 2019
Mikhail G. Brik, Chong-Geng Ma
Taking into account the recurrence relation for the associated Legendre polynomials tPlm=l+m2l+1Pl−1m(t)+l−m+12l+1Pl+1m(t) and their orthogonal properties ∫−11PkmPlmdt=2(l+m)!(2l+1)(l−m)!δkl, we immediately see that the integral in Eq. (3.44) is not zero if l′ = l ±1. This is the selection rule for the orbital quantum number l: An electric dipole transition between two states can be realized if and only if the orbital quantum numbers l in these states differ by unity: Δl = ±1.
Quantum dynamics and spectra of the iodine atom in a strong laser field as calculated with the URIMIR package
Published in Molecular Physics, 2019
R. Marquardt, M. Quack, J. Stohner, I. Thanopulos
Consider a magnetic dipole moment of . In the Gaussian system of units, the magnetic dipole moment becomes . In the Gaussian system of units a magnetic dipole transition induced by a magnetic dipole moment of can thus be considered as an electric dipole transition induced by an electric dipole moment of , just weakened by the numerical factor . Because in the Gaussian system of units the electric field and the magnetic induction field have the same units, one can thus numerically treat magnetic dipole transitions as electric dipole transitions by including the numerical factor in the value of the magnetic dipole matrix element. In such a case, and for a given laser intensity, the value of the field instead of the value of the field is used in the numerical treatment; we however stress that the symmetry rules related to magnetic dipole transitions must be taken into account explicitly in the definition of the coupling matrix elements between the levels included in the numerical simulation.
1,10-Phenanthroline decorated with substituent groups forming europium(III) complexes: synthesis, crystal structure, photoluminescence properties and their bioimaging in living cells
Published in Journal of Coordination Chemistry, 2020
Huimin Song, Congbin Fan, Renjie Wang, Zheng Wang, Shouzhi Pu
The emission spectra of the two complexes exhibited characteristic red emission of Eu(III) ion at room temperature, while emission peaks were not observed for the ligand (Figures 4-6). Energy transfer was effective from the ligands to the central Eu ion. The luminescence spectra of the complexes in different solutions exhibit five characteristic 7Fj sharp peaks (j = 0, 1, 2, 3, 4) coming from the 5D0 emitting state of europium. It is simple to assign the acquired bands to suitable f–f transitions. Here, the five peaks at 580, 590, 615, 650 and 700 nm conform to the 5D0→7F0, 5D0→7F1, 5D0→7F2, 5D0→7F3 and 5D0→7F4 transitions, respectively [49, 50]. The emission spectra of the two compounds are dominated by an intense electric-dipole (5D0→7F2) transition, which led to strong emission of the two complexes Eu(tta)3L1 and Eu(tta)3L2. There are two weak emission peaks at 580 and 650 nm, which were ascribed to forbidden transitions in magnetic and electric dipoles of 5D0→7F0 and 5D0→7F3 transition. The 5D0→7F1 magnetic dipole transition has no connection with the coordination sphere, while the electric dipole transition 5D0→7F2 is susceptible to the nature and symmetry of the coordinating environment.
Luminescence properties of color-tunable YNbO4: Dy3+, Tm3+ phosphors
Published in Journal of Asian Ceramic Societies, 2020
Xin Wang, Xiangping Li, Sai Xu, Lihong Cheng, Jiashi Sun, Jinsu Zhang, Xizhen Zhang, Baojiu Chen
Dy3+ ion, as a luminescent center, has been widely studied in white-light illumination owing to its two characteristic emissions, respectively, locates at around 470 ~ 500 nm and 560 ~ 600 nm corresponding to 4F9/2→6H15/2 (magnetic dipole transition) and 4F9/2→6H13/2 (electric dipole transition) [8,10–12]. The transition intensities of the Dy3+ mainly depend on the host or the crystal-field environment. Usually, the electric dipole transition is hypersensitive to the surrounding environment, while the magnetic dipole transition is insensitive [6,13]. It is reported that when Dy3+ ions occupy at low symmetry sites with no inversion center, the yellow emission is dominated in the emission spectra [10,12,14]. Therefore, it is possible to achieve white-light emission from Dy3+ single-doped materials by adjusting the intensity ratio (Y/B) of yellow to blue emission. However, high-quality white light usually cannot be obtained by Dy3+ single-doped case owing to the deficiency of blue spectral component [15–17]. To solve this problem, an additional blue light-emitting center was usually introduced into Dy3+-activated systems to compensate for the insufficient blue light components. Tm3+ ion is a good blue light compensator because its transition 1D2→3F4 can emit blue emission centered at around 450 nm [18–21]. Moreover, it is also reported that there is an energy transfer between Tm3+ and Dy3+ under ultraviolet (UV) light excitation, and color-controllable emissions were obtained in Dy3+, Tm3+ co-doped phosphors by adjusting the concentrations of Tm3+ and Dy3+ [8,12].