Atomic transition probabilities and tests of the spectroscopic coupling scheme for N i

Abstract

With a wall-stabilized arc source, we have measured the relative transition probabilities of 100 lines of neutral nitrogen in the visible and near-infrared spectrum and have normalized our data to an absolute scale utilizing four recent lifetime results. We estimate that the expanded uncertainties of our data are in the range of +11 -15 %. For a number of 3s -3p and 3p -3d multiplets, we have measured complete sets of lines and observe that most 3p-3d multiplets show considerable departure from LS coupling, while the 3s-3p multiplets adhere to it within +20%. Agreement between intermediate coupling calculations and our experimental data for the 3p-3d multiplets is noticeably better, but significant di6'erences are still encountered for two multiplets originating from the 3d P level.PACS number(s): 32.70.Cs, 32.90.+ a

Experimental Stark broadening studies of the CI transition 3s 1 P 1o − 3p 1 S 0 at 833.5 nm

“…The concave mirror (3) was applied for performing self-absorption checks. By reflecting the radiation reaching this mirror back into the arc and comparing the measured signals, with and without back reflection, conclusions about possible self-absorption effects in the arc plasma could be drawn [16,17]. For our plasma conditions, these checks demonstrated negligible self-absorption in all studied spectral intervals (the investigated CI line, the OI "thermometric" lines as well as the H β transition).…”

Analysis of Line Strength Data for the Spectra οf C(I), N(II), N(I) and O(II)

“…Recent advanced calculations of line strengths [3][4][5][6][7][8][9][10][11][12][13][14][15] provide data for fine structure components which are for some multiplets in good agreement with measured ones, but for other transitions significant departures from LS coupling results as well as from measurements are encountered [16][17][18][19][20][21][22][23][24][25][26][27]. Departures of line strengths from values predicted by the LS coupling scheme are often caused by strong mixing of energy levels belonging to terms with different multiplicity.…”

“…Such level mixing manifests itself by the appearance of LS-forbidden intersystem transitions (see for example Refs. [16][17][18]23]). …”

Diagnostics of Helium-Argon Arc Discharge Plasma Based on Spectral Line Shape Measurements

“…In this manner the number of relative Aki-values normalized to an absolute scale may be substantially increased [5][6][7].…”

“…Usually the relative Aki-values or branching ratios are then normalized to lifetime values of appropriate excited levels. However, because of difficulties in measuring complete sets of transitions involved in the decay of a given level, and because of scarcity of reliable data for many levels, a procedure is often applied allowing the normalization to be expanded over transitions originating from other excited levels [5][6][7]. In such cases the knowledge of the plasma temperature and electron density is of great significance.…”