Silicon   -   Spectral Data for the Chandra X-ray Observatory

• Si VI   (Silicon   Z = 14)

  F I isoelectronic sequence

  Ground state   1s²2s²2p^{5 2}P°_3/2

  Ionization energy 1 655 590 cm^-1 (205.27 eV)

  Data are tabulated for 66 transitions in the range 66 Å to 151 Å. Because of breakdown of LS coupling for F-like ions we mainly selected transition probabilities calculated with intermediate coupling. Mean values between MCHF [1] and CIV3 [2] results are given for the transition arrays 2s²2p⁵-2s²2p⁴3s, 2s²2p⁵-2s²2p⁴3d, and 2s2p⁶-2s²2p⁴3p. Remaining data for 11 transitions 2s²2p⁵-2s²2p⁴nl(n=4,5) and 2s2p⁶-2s2p⁵3s are taken from the Opacity Project (OP) [3]. The multiplet values from OP have been decomposed into fine-structure components assuming LS-coupling, as indicated by the notation LS in the reference column.

    References

  1. G. Tachiev and C. Froese Fischer, The MCHF/MCDHF Collection (Downloaded 22 June, 2002).
      
  2. H.M.S. Blackford and A. Hibbert, At. Data Nucl. Data Tables 58, 101 (1994).
      
  3. NASA TIPTOPbase (Downloaded 1 August, 1995).
     

   

   
• Si VII   (Silicon   Z = 14)

  O I isoelectronic sequence

  Ground state   1s²2s²2p^{4 3}P₂

  Ionization energy 1 988 000 cm^-1 (246.5 eV)

  Data are tabulated for 130 transitions in the range 54 Å to 151 Å. Transition probabilities for the 2s²2p⁴-2s²2p³3s, 2s²2p⁴-2s²2p³3d, and 2s2p⁵-2s2p⁴(⁴P)3s arrays are taken from MCHF calculations [1]. Remaining results are taken from the Opacity Project (OP) [2]. The multiplet values from OP have been decomposed into fine-structure components assuming LS-coupling, as indicated by the notation LS in the reference column.

    References

  1. G. Tachiev and C. Froese Fischer, The MCHF/MCDHF Collection (Downloaded 22 June, 2002).
      
  2. NASA TIPTOPbase (Downloaded 1 August, 1995).
     

   

   
• Si VIII   (Silicon   Z = 14)

  N I isoelectronic sequence

  Ground state   1s²2s²2p^{3 4}S°_3/2

  Ionization energy  2 448 200 cm^-1 (303.54 eV)

  Data are tabulated for 147 transitions in the range 50 Å to 161 Å. Transition probabilities for the 2s²2p³-2s²2p²3s, 2s²2p³-2s²2p²3d, 2s2p⁴-2s2p³(⁵S°)3s, 2p⁵-2s²2p²3s, and 2p⁵-2s²2p²3d are taken from MCHF calculations [1]. Remaining results are taken from the Opacity Project (OP) [2]. The multiplet values from OP have been decomposed into fine-structure components assuming LS-coupling, as indicated by the notation LS in the reference column.

    References

  1. G. Tachiev and C. Froese Fischer, The MCHF/MCDHF Collection (Downloaded 22 June, 2002).
      
  2. NASA TIPTOPbase (Downloaded 1 August, 1995).
     

   

   
• Si IX   (Silicon   Z = 14)

  C I isoelectronic sequence

  Ground state   1s²2s²2p^{2 3}P₀

  Ionization energy 2 832 000 cm^-1 (351.12 eV)

  Data are tabulated for 144 transitions in the range 44 Å to 125 Å. Transition probabilities for the 2s²2p²-2s²2p3s, 2s²2p²-2s²2p3d, 2p⁴-2s²2p3s, and 2p⁴-2s²2p3d arrays are mean values from the MCHF [1] and CIV3 [2] calculations. Values for the 2s2p³-2s2p²3s, 2s2p³-2s2p²3d, 2s²2p²-2s2p²3p, and 2s²2p²-2s²2p4d transitions are taken from the Opacity Project (OP) [3]. Multiplet average results from OP have been decomposed into fine-structure components assuming LS-coupling, as indicated by the notation LS in the reference column.

    References

  1. G. Tachiev and C. Froese Fischer, The MCHF/MCDHF Collection (Downloaded 22 June, 2002).
      
  2. K.M. Aggarwal, Astrophys. J., Suppl. Ser. 118, 589 (1998).
      
  3. NASA TIPTOPbase (Downloaded 1 August, 1995).
     

   

   
• Si X   (Silicon   Z = 14)

  B I isoelectronic sequence

  Ground state   1s²2s²2p ²P°_1/2

  Ionization energy   3 237 300 cm^-1 (401.37 eV)

  Data are tabulated for 143 transitions in the range 34 Å to 170 Å. Transition probabilities for the 2s²2p-2s²3d, 2s2p²-2s2p3s, and 2p³-2s²3d arrays are taken from MCHF [1] calculations. Remaining results aretaken from the Opacity Project (OP) [2]. The multiplet values from OP have been decomposed into fine-structure components assuming LS-coupling, as indicated by the notation LS in the reference column.

    References

  1. G. Tachiev and C. Froese Fischer, The MCHF/MCDHF Collection (Downloaded 22 June, 2002).
      
  2. NASA TIPTOPbase (Downloaded 1 August, 1995).
     

   

   
• Si XI   (Silicon   Z = 14)

  Be I isoelectronic sequence

  Ground state   1s²2s^{2 1}S₀

  Ionization energy 3 842 100 cm^-1 (476.36 eV)

  Data are tabulated for 148 transitions in the range 31 Å to 164 Å. Transition probabilities for the 2s2p-2s3s, 2s2p-2s3d, 2s2p-2p3p, 2p²-2p3s, and 2p²-3d arrays are taken from calculations with the many-body perturbation theory (MBPT) by Safronova et al. [1]. Mean values between MBPT [1] and CIV3 [2] are given for singlets. Remaining results area taken from the Opacity Project (OP) [3]. The multiplet values from OP have been decomposed into fine-structure components assuming LS-coupling, as indicated by the notation LS in the reference column.

  For the transition probability of the 2s^2 1S-2s3p ¹P^o₁ transition (43.763 Å) we give the mean value from several advanced calculations [1,2,4,5]. For the 2s^2 1S-2s3p ³P^o₁ intercombination line (43.760 Å) we give the mean of results of several advanced calculations [1,5,6] and an experimental value from beam foil spectroscopy [7]. This experiment measured lifetimes of the 2s3p ³P^o_0,1,2 levels and the mean wavelength of the 2p^2 3P-2s3p ³P^o transitions. The mean energy of the 2s3p ³P^o term was established as 2 285 210 cm^-1 from this mean wavelength (54.45 Å) and the mean energy of the 2p^2 3P term (448 664 cm^-1). The 2s3p ³P^o term is not included in the NIST Atomic Spectra Database because the previous compilation was done before 1994. Ten transitions involving levels of the 2s3p ³P^o term are included in the present table.

    References

  1. U.I. Safronova, A. Derevianko, M.S. Safronova, and W.R. Johnson, J. Phys. B: At. Mol. Phys. 32, 3527 (1999). (Complete data listing from private communication.)
      
  2. R. Glass, Sol. Phys. 80, 321 (1982).
      
  3. NASA TIPTOPbase (Downloaded 1 August, 1995).
      
  4. L.J. Curtis, S.T. Maniak, R.W. Ghrist, R.E. Irving, D.G. Ellis, M. Henderson, M.H. Kacher, E. Träbert, J. Granzow, P. Bengtsson, and L. Engström, Phys. Rev. A 51, 4575 (1995).
      
  5. S. Fritzsche and I.P. Grant, Phys. Scr. 50, 473 (1994).
      
  6. Yu. I. Ralchenko and L.A. Vainshtein, Phys. Rev. A 52, 2449 (1995).
      
  7. J. Granzow, P.H. Heckmann, and E. Träbert, Phys. Scr. 49, 148 (1994).
     

   

   
• Si XII   (Silicon   Z = 14)

  Li I isoelectronic sequence

  Ground state   1s²2s ²S_1/2

  Ionization energy 4 221 670 cm^-1 (523.42 eV)

  Data are tabulated for 93 transitions in the range 25 Å to 151 Å. Transition probabilities for the 2s-np(n=3-5), 2p-ns(n=3-5), and 2p-nd(n=3-5) arrays are taken from calculations by Zhang et al.[1] with relativistic atomic structure and distorted wave collision strength programs. Remaining results are taken from the Opacity Project (OP) [2]. The multiplet values from OP have been decomposed into fine-structure components assuming LS-coupling, as indicated by the notation LS in the reference column. Level values with square brackets are from precise calculations as derived in the introduction.

    References

  1. H.L. Zhang, D.H. Sampson, and C.J. Fontes, At. Data Nucl. Data Tables 44, 31 (1990).
      
  2. NASA TIPTOPbase (Downloaded 1 August, 1995).