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Introduction: Treatment of multiple brain metastases by linac‐based stereotactic radiotherapy (SRT) can employ either a multiple‐isocenter (MI) or single‐isocenter (SI) approach. The purposes of this study were to evaluate the dosimetric results of MI and SI approaches and compare the impacts of intra‐fractional setup discrepancies on the robustness of respective approaches using isocenter shifts, whether the same magnitude of translational and rotational effects could lead to a significant difference between the two approaches. Methods: Twenty‐two patients with multiple brain metastases treated by linac‐based SRT were recruited. Treatment plans were computed with both the MI and SI approaches. For the MI approach, the isocenter was located at the geometric center of each planning target volumes (PTVs), whereas the isocenter of the SI approach was located midway between the PTV centroids. To simulate the intra‐fractional errors, isocenter displacements including translational and rotational shifts were hypothetically applied. Apart from the dosimetric outcomes of the two approaches, the impact of the isocenter shifts on PTVs and organs at risk (OARs) were recorded in terms of the differences (δ) in dose parameters relative to the reference plan and was then compared between the MI and SI approaches. Results: Both MI and SI plans met the plan acceptance criteria. The mean Paddick conformity index (Paddick CI) and Dmax of most OARs between MI and SI plans did not show a significant difference, except that higher doses to the left optic nerve and optic chiasm were found in SI plans (p = 0.03). After the application of the isocenter shifts, δCI increased with an increase in the magnitude of the isocenter shift. When comparing between MI and SI plans, the δCIs were similar (p > 0.05) for all extents of translational shifts, but δCIs were significantly higher in SI plans after application of all rotations particularly ±1.5° and ±2.0° shifts. Despite the result that the majority of δDMax of OARs were higher in the SI plans, only the differences in the left optic nerve and chiasm showed generally consistent significance after both translational ≥±1 mm and rotational shifts of ≥±1∘$^\circ $. Conclusion: Both MI and SI approaches could produce clinically acceptable plans. However, isocenter shifts brought dosimetric impacts to both MI and SI approaches and the effects increased with the increase of the shift magnitude. Although similar impacts were shown in plans of both approaches after translational isocenter shift, SI plans were relatively more vulnerable than MI plans to rotational shifts. [ABSTRACT FROM AUTHOR]

The laser induced fluorescence spectrum of palladium dimer (Pd2) in the visible region between 480 and 700 nm has been observed and analyzed. The gas-phase Pd2 molecule was produced by laser ablation of palladium metal rod. Eleven vibrational bands were observed and assigned to the [17.1]3Πg-X3Σu+ transition system. The bond length (ro) and vibrational frequency (ΔG1/2) of the ground X3Σu+ state were determined to be 2.47(4) Å and 211.4(5) cm-1, respectively. A molecular orbital energy level diagram was used to understand the observed ground and excited electronic states. This is the first gas-phase experimental investigation of the electronic transitions of Pd2. [ABSTRACT FROM AUTHOR]

The electronic transition spectrum of platinum monoboride (PtB) radical has been observed for the first time. Using laser vaporization/reaction free jet expansion and laser induced fluorescence spectroscopy, the optical spectrum of PtB in the visible region between 455 and 520 nm has been studied. Gas-phase PtB molecule was produced by the reaction of diborane (B2H6) seeded in argon and laser ablated platinum atom. Seven vibrational bands of the Pt11B radical have been recorded and analyzed. The observation of Pt isotopic molecules and the Pt10B isotope confirmed the carrier of the bands. Two different transition systems, namely: the [20.2]3/2-X2Σ+ and the [21.2]1/2-X2Σ+ systems were identified. PtB was determined to have an X2Σ+ ground state and the bond length, re, was determined to be 1.741 Å. [ABSTRACT FROM AUTHOR]

Electronic transition spectrum of cobalt monoboride (CoB) in the visible region between 495 and 560 nm has been observed and analyzed using laser-induced fluorescence spectroscopy. CoB molecule was produced by the reaction of laser-ablated cobalt atom and diborane (B2H6) seeded in argon. Fifteen vibrational bands with resolved rotational structure have been recorded, which included transitions of both Co10B and Co11B isotopic species. Our analysis showed that the observed transition bands are ΔΩ = 0 transitions with Ω″ = 2 and Ω″ = 3 lower states. Four transition systems have been assigned, namely, the [18.1]3Π2-X3Δ2, the [18.3]3[uppercase_phi_synonym]3-X3Δ3, the [18.6]3- X3Δ3, and the [19.0]2-X3Δ2 systems. The bond length, ro, of the X 3Δ3 state of CoB is determined to be 1.705 Å. The observed rotational lines showed unresolved hyperfine structure arising from the nuclei, which conforms to the Hund's case (aβ) coupling scheme. This work represents the first experimental investigation of the CoB spectrum. [ABSTRACT FROM AUTHOR]

Two new electronic transition systems, namely, the [14.0]2[uppercase_phi_synonym]7/2-Χ 2Δ5/2 and the [15.7]2[uppercase_phi_synonym]5/2-Χ 2Δ5/2 transitions were observed and analyzed using laser vaporization/reaction supersonic free jet expansion and high resolution laser induced fluorescence spectroscopy. In addition, the (v, 0) bands with v=6–10 of the [14.6]2Δ5/2-Χ 2Δ5/2 transition were found to be perturbed by the [15.7]2[uppercase_phi_synonym]5/2 state. The interaction between the [14.6]2Δ5/2 and the [15.7]2[uppercase_phi_synonym]5/2 states is evident in the progressive increase in hyperfine width of rotational lines of the [14.6]2Δ5/2-X 2Δ5/2 transition as the vibrational quantum number increases. Deperturbation procedures were successfully applied to analyze the interaction between these two states. All observed spectra show partially resolved hyperfine structure, and the hyperfine width decreases rapidly as J increases suggested that the hyperfine structure conforms to the Hund’s case aβ coupling scheme. Accurate molecular and hyperfine constants for the [14.0]2[uppercase_phi_synonym]7/2, the [14.6]2Δ5/2 and the [15.7]2[uppercase_phi_synonym]5/2 states were obtained and analyzed. [ABSTRACT FROM AUTHOR]

High resolution laser induced fluorescence spectrum of IrB in the spectral region between 545 and 610 nm has been recorded and analyzed. Reacting laser-ablated iridium atoms with 1% B2H6 seeded in argon produced the IrB molecule. This is the first experimental observation of the IrB molecule. Four vibronic transition bands, (v,0) with v=0–3 of an electronic transition system, have been observed. Spectra of all four isotopic molecules, 191Ir10B, 193Ir10B, 191Ir11B, and 193Ir11B, were recorded. Isotopic relationships confirmed the carrier of the spectra and the vibrational quantum number assignment. Preliminary analysis of rotational lines showed that these vibronic bands are with Ω′=2 and Ω″=3. The electronic transition identified is assigned as the [16.5]3Π2-X 3Δ3 system. Partially resolved hyperfine structure which conforms to the Hund’s case aβ coupling scheme has been observed and analyzed. The bond length r0 of the lower X 3Δ3 state of IrB was determined to be 1.7675 Å. [ABSTRACT FROM AUTHOR]

Laser induced fluorescence spectrum of NiBr in the visible region between 604 and 666 nm has been recorded and analyzed. Fourteen bands belonging to three electronic transition systems, namely, [15.1] 2Δ5/2–X 2Π3/2, [15.1] 2Π3/2–X 2Π3/2, and [14.0] 2Δ5/2–X 2Π3/2 have been observed. Spectra of isotopic molecules were also observed and analyzed. Detailed analysis of the recorded spectra indicated that the two electronic states [15.1] 2Π3/2 and [15.1] 2Δ5/2 lie about 1 cm-1 apart from each other and J-dependent perturbation due to spin-uncoupling interaction has been observed. Least squares fitting procedures involving deperturbation matrix elements were used to fit the observed line positions, which yielded accurate molecular constants for the [15.1] 2Π3/2 and [15.1] 2Δ5/2 states. In addition, the (1,0) band of the [15.1] 2Δ5/2–X 2Π3/2 transition shows partially resolved hyperfine structure that was caused by the interaction of unpaired electron with the magnetic moment of the Br nucleus (nuclear spin of I=3/2) in the excited state. The rapid decrease in hyperfine width as J increases suggests that the hyperfine coupling in the excited state conforms to Hund’s case (aβ) coupling scheme. [ABSTRACT FROM AUTHOR]

Photoabsorption measurements of NO bands have been made by vacuum-ultraviolet Fourier transform spectrometry with a resolution of 0.12 cm-1 in the wavelength region of 166.2–196.2 nm. Accurate line positions are obtained for the δ(υ,0) bands with υ=2, 3, the ε(υ,0) bands with υ=2, 3, and the β(υ,0) bands with υ=10,12,14. Absolute term values are found for the corresponding upper levels C(2,3), D(2,3), and B(10,12,14). Accurate rotational line integrated cross sections have also been obtained for the lines in these bands. Integrated cross sections reported in our earlier papers [J. Chem. Phys. 109, 1751 (1998); 112, 2251 (2000); 115, 3719 (2001); 116, 155 (2002); 117, 10621 (2002); 119, 8373 (2003)] have been revised, and the results reported here comprise the δ(υ,0) bands with υ=0–3, the ε(υ,0) bands with υ=0–3, the β(υ,0) bands with υ=6,7,9–12,14, and the γ(3,0) band. For each band, the band oscillator strength is obtained from the sum of the line strengths of all rotational lines, and these are compared with other published values. [ABSTRACT FROM AUTHOR]

Laser-induced fluorescence spectrum of NiI in the near infrared region of 714–770 nm has been recorded. Seven bands belonging to three electronic transition systems were observed and analyzed: the (0,0), (1,0), and (2,0) bands of [13.3] 2Σ+-A 2Π3/2 system; the (1,1) and (0,1) bands of [13.9] 2Π3/2-X 2Δ5/2 system; and the (0,0) and (1,0) bands of [13.9] 2Π3/2-A 2Π3/2 system. Spectra of isotopic molecules confirmed the vibrational quantum number assignment of the observed bands. Least-squares fit of rotationally resolved transition lines yielded accurate molecular constants for the v=0–2 levels of the [13.3] 2Σ+ state, the v=0 level of the A 2Π3/2, and the v=1 level of the X 2Δ5/2 state. The vibrational separation, ΔG1/2, of the ground state was measured to be 276.674 cm-1. With the observation of the [13.9] 2Π3/2-A 2Π3/2 and [13.9] 2Π3/2-X 2Δ5/2 transitions, we accurately determined the energy separation between the A 2Π3/2 and the X 2Δ5/2 to be 163.847 cm-1. This confirms that the order of the A 2Π3/2 and X 2Δ5/2 states in NiI is reversed when compared with other nickel monohalides. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

High-resolution laser-induced fluorescence spectrum of a jet-cooled NiI molecule has been recorded in the near infrared and visible regions. The NiI molecule was produced by reacting laser-ablated nickel atom and methyl iodide (CH[sub 3]I). Three electronic states have been identified that include the X [sup 2]Δ[sub 5/2] and two low-lying [13.9] [sup 2]Π[sub 3/2] and [14.6] [sup 2]Δ[sub 5/2] excited states. Molecular transition bands (v[sup ′],0) of the [13.9] [sup 2]Π[sub 3/2]-X [sup 2]Δ[sub 5/2] system with v[sup ′]=0, 4–9, and the (v[sup ′],0) bands of the [14.6] [sup 2]Δ[sub 5/2]-X [sup 2]Δ[sub 5/2] system with v[sup ′]=0–6 were observed and analyzed. Spectra of isotopic molecules confirmed the assignment of vibrational quantum number of the observed bands. Least squares fit of rotational transition lines yielded accurate molecular constants for the states studied. The bond length r[sub 0] measured for the X [sup 2]Δ[sub 5/2] is 2.3479 Å and the equilibrium bond length, r[sub e], for the [13.9] [sup 2]Π[sub 3/2] and [14.6] [sup 2]Δ[sub 5/2] are, respectively, 2.4834 and 2.5081 Å. With the use of a molecular orbital energy level diagram, we have examined the electronic configurations that give rise to the X [sup 2]Π[sub 3/2] ground state for NiF, NiCl, and NiBr, but the X [sup 2]Δ[sub 5/2] state for NiI. This work represents the first spectroscopic study of the NiI molecule. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The ε(0,0) (D [sup 2]Σ[sup +]–X [sup 2]Π[sub r]) band of NO has been recorded by using a vacuum ultraviolet Fourier transform spectrometer from Imperial College, London, with synchrotron radiation at the Photon Factory, KEK, Japan, as a continuum light source. Analysis of the ε(0,0) band provides accurate rotational line positions and term values as well as the photoabsorption cross sections. Molecular constants of the v=0 level of the D [sup 2]Σ state have been determined as T[sub 0]=53 291.10±0.10 cm[sup -1], B[sub 0]=1.991 07±0.000 05 cm[sup -1], and D[sub 0]=(6.6±0.1)×10[sup -6] cm[sup -1]. Accurate rotational line strengths have also been obtained and the sum of the line strengths for all rotational lines is determined as 2.18×10[sup -15] cm[sup 2] cm[sup -1]. The band oscillator strength of the ε(0,0) band is determined to be (2.47±0.12)×10[sup -3]. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Electronic transitions of cobalt monochloride and cobalt monoiodide have been studied using laser vaporization-reaction free jet expansion and laser induced fluorescence spectroscopy in the near infrared region. The observed transitions have been identified as the [10.3] 3Φ[SUB4]-X 3Φ[SUB4] transition of CoCl and [11.0] 3Φ[SUB4]-X 3Φ[SUB4] transition of CoI. The magnetic hyperfine structure arising from the cobalt nucleus with I = 7/2 was resolved and analyzed. Accurate rotational and hyperfine parameters for the [10.3] 3Φ[SUB4] and X 3Φ[SUB4] states of CoCl and [11.0] 3Φ[SUB4] and X 3Φ[SUB4] states of CoI have been obtained. Comparison of Fermi contact parameters, b[SUBF], for the upper states indicated that the observed [10.3] 3Φ[SUB4]-X 3Φ[SUB4] transition of CoCl and [11.0] 3Φ[SUB4]-X 3Φ[SUB4] transition of CoI have arisen from the promotion of an electron from the bonding s orbital to a slightly antibonding σ orbital. Observed low-lying 3Φ states of the cobalt monohalides and hydride are also compared and discussed. [ABSTRACT FROM AUTHOR]

The electronic structures and spectroscopic parameters of the ground and some low-lying excited states of the first-row transition metal phosphides have been calculated with the density functional theory using the Becke three-parameter hybrid exchange functional with the Lee-Yang-Parr correlation functional (B3LYP). The ground states of the transition metal phosphides are found to be [SUP1]∑[SUP+] (ScP), [SUP2]Δ (TiP), [SUP3]Δ (VP), [SUP4]∑[SUP-] (CrP), [SUP5]Π (MnP), [SUP6]∑[SUP-] (FeP), [SUP5]Δ (CoP), [SUP4]Δ (NiP), and [SUP3]∑[SUP-] (CuP). The B3LYP functional predicts an increase in covalent character in the bonds between the metal and the phosphorus across the transition metal series. The energies of the low-lying excited states relative to the ground state for TiP, FeP, and CoP have been found to be so small that many low-lying states are possible candidates to be the ground state. [ABSTRACT FROM AUTHOR]

The (0,0) band of the B ²Σ[sup +]-X²Σ[sup +] transition of LaS near 726 nm has been studied at high resolution using laser vaporization/reaction supersonic free jet expansion and laser induced fluorescence spectroscopy. Spectra taken at a resolution of about 50 MHz show resolved hyperfine structure which is caused principally by the unpaired 6sσ- electron in the ground state interacting with large magnetic moment of the [sub 57][sup 139]La nucleus with nuclear spin I=7/2. The X²Σ[sup +] state of LaS is in good Hund's case (b[sub βs]) coupling, however, the upper state, B ²Σ[sup +], is close to case (b[sub βJ]) coupling. A total of 1850 rotational-hyperfine transition lines have been assigned and measured. Accurate rotational, spin and hyperfine parameters for the B ²Σ[sup +] and X²Σ[sup +] states have been obtained, which give information about the electron distribution in the molecule. [ABSTRACT FROM AUTHOR]

Four electronic states of NiBr have been studied using the technique of laser vaporization/reaction with supersonic cooling and laser induced fluorescence (LIF) spectroscopy. NiBr molecules were produced by reacting laser ablated nickel atoms and ethyl bromide (C[sub 2]H[sub 5]Br). High resolution LIF spectrum between 724 and 810 nm was recorded, which consists of the (2,0), (1,0), and (0,0) bands of the [13.2] ²Π[sub 3/2-]-X²Π[sub 3/2] system and the [13.2] ²Π[sub 3/2]--A ²Δ[sub 5/2] system, and also the (v,0) with v = 0-4 bands of the [12.6] 2Σ[sup +]-X²Π[sub 3/2] system. Spectra of four isotopic molecules: [sup 58]Ni[sup 79]Br, [sup 58]Ni[sup 81]Br, [sup 60]Ni[sup 79]Br, and [sup 60]Ni[sup 81]Br were observed and analyzed. Least squares fit of rotationally resolved transition lines yielded accurate molecular constants for the X²Π[sub 3/2], A ²Δ[sub 5/2], [12.6] 2Σ[sup +], and [13.2] ²Π[sub 3/2] electronic states of NiBr. The bond length, r[sub 0], measured for the X²Π[sub 3/2] and A ²Δ[sub 5/2] states is 2.19628 and 2.16445 Å, respectively. A molecular orbital diagram has been constructed to explain the four observed electronic states. This work represents the first high-resolution spectroscopic study of NiBr. [ABSTRACT FROM AUTHOR]

The β(6,0) (B [sup 2]Π[sub r]–X [sup 2]Π[sub r]) and γ(3,0) (A [sup 2]Σ[sup +]–X [sup 2]Π[sub r]) bands of NO have been recorded using a vacuum ultraviolet Fourier transform spectrometer with synchrotron radiation as light source. The analysis of the β(6,0) and γ(3,0) bands of NO provides accurate rotational line positions and term values. Molecular constants of the v=6 level of the B [sup 2]Π[sub r] and v=3 level of the A [sup 2]Σ[sup +] have been determined. Accurate rotational line strengths have also been obtained. The band oscillator strength of the β(6,0) and γ(3,0) bands are determined to be 0.48×10[sup -4] and 2.69×10[sup -4], respectively. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The predissociation linewidths and level shifts of vibrational levels of three oxygen isotopic molecules 16O2, 16O18O, and 18O2 arising from the interactions of the B 3Σ-u state with the four repulsive states 5Πu, 3Σ+u, 3Πu, and 1Πu, have been calculated. A set of parameters characterizing these interactions has been determined. Good agreement between calculated and experimental predissociation widths and shifts has been obtained for all the three isotopic molecules. [ABSTRACT FROM AUTHOR]

Predissociation linewidths of the (3,0)–(11,0) Schumman–Runge bands of 18O2 and 16O 18O in the wavelength region 180–196 nm have been obtained from the published measurements of the absolute absorption cross sections of Yoshino et al. [Planet. Space Sci. 36, 1201 (1988); 37, 419 (1989)] and spectroscopic constants of these molecules of Cheung et al. [J. Mol. Spectrosc. 131, 96 (1988); 134, 362 (1989)]. The linewidths are determined as parameters in the nonlinear least-squares fitting of calculated to measured cross sections. Predissociation maxima are found at upper vibrational levels with v’=4, 7, and 10 for 18O2 and for 16O 18O. Our predissociation linewidths are mostly greater than previous experimental values for both isotopic molecules. [ABSTRACT FROM AUTHOR]

Presents a correction to the article related to the application of a VUV Fourier transform spectrometer and synchrotron radiation source to measurements of absorption bands of nitrogen oxide, published in previous issues of "Journal of Chemical Physics."

It is demonstrated that, according to semi-classical theory, the isotopic dependence of the predissociation linewidths in the Schumann-Runge bands of oxygen cannot be removed by simple scaling of the reduced mass. This is in contrast to the isotopic dependence of the predissociated vibrational energy levels. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Comments on an study on the predissociation of oxygen in the B state. Distinction which confirms that the simulated spectra are excitation spectra and not absorption spectra; Criticism on the conclusions concerning the predissociation.