A schematic drawing of experimental setup under crossed beam condition for the chemiluminescence detection. SK1, SK2: skimmers 1mm in diameter. C1, C2, C3, C4: collimators 10, 4, 2, and 3 mm in diameter, respectively. BS: beam stop 3 mm in diameter. HP: 800 mm long hexapole field constructed of 6 mm ϕ rods. P.M.: photomultipliers. FL: band pass filter. M: concave mirror. GF: guiding field (5 kVcm−1, 350 mm long). OF: orientation field (15 kVcm−1, 100 mm long).
CH focusing curves, , measured by the saturated laser-induced fluorescence method at R-branch in A2Δ3/2 ← X2Π1/2 transition for the six rotational |J, Fi〉 states. (Symbols) Experimental: (1) (◯) |1/2, F2〉, (2) (●) |3/2, F1〉, (3) (□) |3/2, F2 〉, (4) (▪) |5/2, F1〉, (5) (△) |5/2, F2〉 and (6) (▲) |7/2, F1〉. (◆) Overall CH focusing curve, , as the superposition of the focusing curves for the six |J, Fi〉 rotational states.
(a) Scaling factors, , measured at the two representative hexapole voltages; (●) 4 kV, (◯) 6 kV. (□) The relative intensities of ; the R corresponding to those at three O2 beam conditions in Fig. 3(b) are designated by (a–c), respectively. (▪) The R observed in our recent study under the beam-cell condition (cited from Ref. 17). (b) CL-focusing curves, , measured at the three O2 beam conditions; (●) , (□) , (◯) . (Dashed line) Overall CH focusing curve, . For comparison, they are plotted after normalization by their intensity at a hexapole voltage of 4 kV. The relative intensities at each O2 beam condition are designated by the dashed arrows (a–c), respectively.
CL-focusing curves, , measured at the four O2 conditions. Crossed beam conditions: (a) , (B) , (C) . Beam-cell condition (cited from Ref. 20): (D) Cell. (◆) Experimental, (Dashed lines) Calculated CL-focusing curves by using Eq. (12). The contributions of each rotational state are shown by the symbols: (◯) |1/2, F2〉, (●) |3/2, F1〉, (□) |3/2, F2〉, (▪) |5/2, F1〉, (△) |5/2, F2〉, (▲) |7/2, F1〉.
Left column: (Painted bars) The RSSRCS-CH, , obtained by the fitting of using Eq. (12) at the four O2 conditions; (a) , (b) , (c) , (d) Cell (cited from Ref. 21). The RSSRCS-CH are scaled by the cross section of for the |1/2, F2〉 state which is calibrated by using the RSSRCS-CH under the beam-cell condition (Ref. 18). Right column: Rotational state distributions of O2, , at the four O2 conditions; (A) (Trot = 10 K), (b) (Trot = 25 K), (C) (Trot = 180 K), (C) Cell (Trot = 300 K).
Correlations of the population of O2 in the (s = 1∼5) rotational states with the RSSRCS-CH, ; (●) |1/2, F2〉, (●) |3/2, F1〉, (▪) |N = 2〉 (|3/2, F2〉 and |5/2, F1〉). (a) , (Solid line) Correlation with , (b) , (Dashed line) Correlation with , (c) . No clear correlation is recognized for the N = 2 rotational states with any rotational states.
A schematic drawing of the initial step for the title reaction at three orientational configurations of CH; H-end, sideways, and C-end. The intermediate 2HCOO (IM1, 2A′) has the structure in which the C atom of CH binds to one of the O atoms of O2 molecule with a H–C–O angel of 118°. The reaction coordinate for the TS1 transmission is related to the internal motions in the intermediate (IM1) along the C–O–O bending angle and along the dihedral angle of CH bond out of the C–O–O plane; these reaction coordinates correspond to the correlated rotational motions between CH and O2 whose planes of rotation are orthogonal each other; O2 rotation is in the C–O–O plane (painted plane) whereas CH rotation is out of the C–O–O plane. Since the 1M1 formation has no energy barrier and is strongly exothermic, the strong attractive force causes no dependence of CH orientation (and alignment) on the 1M1 formation.
Characteristics of the O2 beams at different conditions.
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