“…Even at the resolution of the current experiment, each band appears to contain several heads. The resolution used here does not permit the position of these heads to be accurately determined, however, the band centers observed correlate well with those reported by Hayes and Nevin . The features observed are fit to near the experimental error with a linear least squares fit, however, a nonlinear fit provides a slightly better result.…”
Section: Resultssupporting
confidence: 79%
“…The strongest features are the z 8 P 7/2 −a 6 S 5/2 , the z 8 P 5/2 −a 6 S 5/2 , and the z 6 P 7/2 −a 6 S 5/2 manganese atom transitions . The A 7 Π−X 7 Σ transition and the system II and III bands of MnCl are easily identified (Table ). Two broad structureless features at 464 and 720 nm and at least three broad blended features in the 530 nm region are also apparent.…”
The chemiluminescent reactions between an agglomerated flux of entrained manganese vapor (atoms and small manganese molecules) and halogen vapor (chlorine or fluorine) have been investigated under multiple collision conditions. Both reaction groups produce emission features that are readily correlated with manganese atom transitions, manganese(I) halide molecular emission, and broad features centered at 464, 530, and 720 nm which might be attributed to the manganese cluster halides or to manganese dimer. Chemical reactions involving manganese atoms and small manganese clusters are required to explain the observed emission features. The energetics of several possible metal atom, dimer, and trimer reactions are considered and correlated with the observed emission features. The energetics of some of these reactions are used to estimate the a 5 Σ-X 7 Σ energy separation in MnF. This value, 2500 ( 500 cm -1 , is consistent with the value of 1743 cm -1 determined for MnH and a value of 3000 ( 500 cm -1 estimated previously for MnF. Vibrationally resolved emission features are observed for five previously investigated MnF transitions. While limited information was obtained for the system a (350 nm), c (504 nm), or d (690 nm) transitions, revised vibrational analyses for the b (495 nm) and the e (832 nm) band systems of MnF are presented. The b system bands are found to be blue degraded, with a vibrational analysis suggesting that the observed transition terminates in the X 7 Σ ground state. Twenty bands belonging to the origin sequence of the e system have been identified and fit using a nonlinear least squares analysis. Energetic arguments dictate that the lower state of this transition must be either the ground state or an electronic state differing little in energy from the ground state.
“…Even at the resolution of the current experiment, each band appears to contain several heads. The resolution used here does not permit the position of these heads to be accurately determined, however, the band centers observed correlate well with those reported by Hayes and Nevin . The features observed are fit to near the experimental error with a linear least squares fit, however, a nonlinear fit provides a slightly better result.…”
Section: Resultssupporting
confidence: 79%
“…The strongest features are the z 8 P 7/2 −a 6 S 5/2 , the z 8 P 5/2 −a 6 S 5/2 , and the z 6 P 7/2 −a 6 S 5/2 manganese atom transitions . The A 7 Π−X 7 Σ transition and the system II and III bands of MnCl are easily identified (Table ). Two broad structureless features at 464 and 720 nm and at least three broad blended features in the 530 nm region are also apparent.…”
The chemiluminescent reactions between an agglomerated flux of entrained manganese vapor (atoms and small manganese molecules) and halogen vapor (chlorine or fluorine) have been investigated under multiple collision conditions. Both reaction groups produce emission features that are readily correlated with manganese atom transitions, manganese(I) halide molecular emission, and broad features centered at 464, 530, and 720 nm which might be attributed to the manganese cluster halides or to manganese dimer. Chemical reactions involving manganese atoms and small manganese clusters are required to explain the observed emission features. The energetics of several possible metal atom, dimer, and trimer reactions are considered and correlated with the observed emission features. The energetics of some of these reactions are used to estimate the a 5 Σ-X 7 Σ energy separation in MnF. This value, 2500 ( 500 cm -1 , is consistent with the value of 1743 cm -1 determined for MnH and a value of 3000 ( 500 cm -1 estimated previously for MnF. Vibrationally resolved emission features are observed for five previously investigated MnF transitions. While limited information was obtained for the system a (350 nm), c (504 nm), or d (690 nm) transitions, revised vibrational analyses for the b (495 nm) and the e (832 nm) band systems of MnF are presented. The b system bands are found to be blue degraded, with a vibrational analysis suggesting that the observed transition terminates in the X 7 Σ ground state. Twenty bands belonging to the origin sequence of the e system have been identified and fit using a nonlinear least squares analysis. Energetic arguments dictate that the lower state of this transition must be either the ground state or an electronic state differing little in energy from the ground state.
“…Of those shown in the figure, only the UV system had been definitely assigned, as A 7 Π → X 7 Σ + (a far-UV system not shown on the figure, and designated B 7 Σ + → X 7 Σ + , had also been detected for MnF and MnCl , ). For the rest, analysis of the vibrational, and in some cases rotational, structure had allowed a number of vibrational constants, ν 00 values, and probable term symbols of the participating state pairs to be deduced, but neither the exact identity of the lower state of the transition nor its excitation energy was known. 1 Schematic representation of the electronic spectroscopy of the Mn monohalides, MnX, ,− as known at the time of our recent Mn + SnCl 4 report . The MnCl bands marked ?…”
Section: Introductionmentioning
confidence: 99%
“…Schematic representation of the electronic spectroscopy of the Mn monohalides, MnX, ,− as known at the time of our recent Mn + SnCl 4 report . The MnCl bands marked ?…”
Chemiluminescence in four different MnCl band systems
e5Σ+ → a5Σ+
(“blue”), d5Π → a5Σ+
(“green”),
c5Σ+ → a5Σ+
(“red”), and b5Π → a5Σ+
(“infrared”) has been observed from the interaction of a
laser-ablated beam of Mn atoms with gaseous SiCl4. The
initial translational thresholds range from ∼150 to
∼300
kJ mol-1, increasing in the order
e5Σ+ < c5Σ+
∼ d5Π < b5Π. Analysis of the
measured excitation functions,
in terms of a multiple line-of-centers model [Levy, M. R.
Res. Chem. Kinetics
1993,
1, 163], shows that, with
the exception of a high-energy c5Σ+ channel
contribution to d5Π production and possibly a joint
c5Σ+/d5Π
production process at low energies, all the reactions take place on
distinct potential surfaces. Although, on
energetic grounds, the b5Π and
c5Σ+ channels could derive from reaction of
ground-state Mn(a6S) atoms, the
first excited state, a6DJ, is the most likely
reagent species in all cases, indicating substantial excess
barriers.
In contrast to the corresponding SnCl4 reactions, only
the c5Σ+ excitation function reveals a
shift forward in
transition-state location with increasing collision energy. The
results have been rationalized in terms of a
hierarchy of ionic−covalent curve crossings at short internuclear
distances.
“…Most of the MnF and MnCl band systems observed have been well characterised spectroscopically, [24][25][26][27][28][29][30][31][32][33] the main exception being e 5 S + -a 5 S + , which was originally reported as a fragment in absorption by Mesnage, 24 and which was assigned in this laboratory 17,18 by analogy with MnH. 34 For both monohalides the A 7 P-X 7 S + , e 5 S + -a 5 S + and d 5 P-a 5 S + systems fall in the same respective detection regions, i.e.…”
A combined experimental and time-dependent density functional theory (TDDFT) investigation of the title reaction is presented. Both 'hot' and 'cold' laser-ablated Mn atom beams have been employed to determine the translational excitation functions for production of MnCl*(c(5)Σ(+), d(5)Π, e(5)Δ, e(5)Σ(+), A(7)Π). Analysis in terms of the multiple line-of-centres approach shows that the 'hot' results are dominated by reactions of the second metastable state of Mn, z(8)P(J), all with very low thresholds; while the first metastable state, a(6)D(J), and the ground state, a(6)S, are the precursors in the 'cold' results, all with significant excess barriers. The post-threshold behaviour of most z(8)P(J) and a(6)D(J) reaction channels implies that the transition states shift forward with increasing collision energy. The TDDFT calculations suggest that, while Mn*(z(8)P(J), a(6)D(J)) insertion into the S-Cl bond is facile, the observed chemiluminescence channels mostly derive from abstraction in a preferred linear Mn-Cl-S configuration, and that the low z(8)P(J) thresholds originate from attractive but excited reagent potentials which either reach a seam of interactions in the product valley or (in the c(5)Σ(+) case) lead to an octet potential very close in energy to the product sextet. The excess barriers in the Mn*(a(6)D(J)) and Mn(a(6)S) reactions appear for the most part to derive from exit channel mixing with lower-lying product potentials. The observed transition state shifts are consistent with the system being forced to ride up the repulsive wall of the entrance valley as collision energy increases, the location of that wall being different for the z(8)P(J) and a(6)D(J) cases.
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