Shih et al. Nanoscale Research Letters 2011, 6:409 http://www.nanoscalereslett.com/content/6/1/409 Page 5 of 7 Figure 8 PLE spectrum of QD2 recorded at 1.4 K with detection energy fixed. structures can be modified by the effects of the diamag- netic shift or Zeeman splitting. The energy level modifi- cation due to the diamagnetic shift is relative small (approximately 1 to 2 meV) even at a magnetic field intensity of 14 T. The amount of energy splitting due to Zeeman effect, ΔEZeeman, is given by the following equa- tion: EZeeman = m 2emh¯∗ B, where mℓ is the angular quantum number of the 0D quantum structures, e is the electron charge, ħ is the Planck’s constant, and B is the magnetic field. For excited state carrying angular momentum mℓ of ± 1 (p-like state), the amount of energy splitting can be expressed as eh¯ B. By placing an effective mass of EZeeman = 2 × 2m∗ 0.05 m0 (for the InAs/GaAs quantum structures) into the above equation, a splitting in energy of about 32.39 meV was obtained for the p-like excited state transition. This number is quite close to the energy splitting (approximately 33 meV) of the resonance measured at 158 meV in our PLE spectrum. For the s-like transition, only the diamagnetic shift of approximately 1 meV is shown because mℓ = 0. Therefore, the two peaks that appeared at 158 and 222 meV in the PLE spectra resulted from the transitions of p-like and s-like excited states, respectively. In Figure 10a, b, the PL and PLE spectra from QD1 and QD2 at 1.4 K were displayed in parallel with the bottom horizontal axis representing the energy with respect to the WL absorption edge at 1.42 eV. As clearly Figure 9 Magnetic field-dependent PLE spectra of QD2 recorded at 1.4 K from B = 0 T to B = 14 T. Figure 10 PL and PLE spectra recorded at 1.4 K were plotted as a function of energy.