Photodissociation channels for N2O near 130 nm studied by product imaging

The photodissociation of N(2)O at wavelengths near 130 nm has been investigated by velocity-mapped product imaging. In all, five dissociation channels have been detected, leading to the following products: O((1)S)+N(2)(X (1)Sigma), N((2)D)+NO(X (2)Pi), N((2)P)+NO(X (2)Pi), O((3)P) + N(2)(A (3)Sigma(+) (u)), and O((3)P) + N(2)(B (3)Pi(g)). The most significant channel is to the products O((1)S) + N(2)(X(1)Sigma), with strong vibrational excitation in the N(2). The O((3)P) + N(2)(A,B):N((2)D,(2)P) + NO branching ratio is measured to be 1.4 +/- 0.5, while the N(2)(A) + O((3)P(J)):N(2)(B) + O((3)P(J)) branching ratio is determined to be 0.84+/-0.09. The spin-orbit distributions for the O((3)P(J)), N((2)P(J)), and N((2)D(J)) products were also determined. The angular distributions of the products are in qualitative agreement with excitation to the N(2)O(D (1)Sigma(+)) state, with participation as well by the (3)Pi(v) state.     

Communication: vacuum ultraviolet laser photodissociation studies of small molecules by the vacuum ultraviolet laser photoionization time-sliced velocity-mapped ion imaging method

We demonstrate that the vacuum ultraviolet (VUV) photodissociation dynamics of N(2) and CO(2) can be studied using VUV photoionization with time-sliced velocity-mapped ion imaging (VUV-PI-VMI) detection. The VUV laser light is produced by resonant sum frequency mixing in Kr. N(2) is used to show that when the photon energy of the VUV laser is above the ionization energy of an allowed transition of one of the product atoms it can be detected and characterized as the wavelength is varied. In this case a β parameter = 0.57 for the N((2)D°) was measured after exciting N(2)(o(1)Π(u), v(') = 2, J(') = 2) ← N(2)(X(1)Σ(g) (+), v(") = 0, J(") = 1). Studies with CO(2) show that when there is no allowed transition, an autoionization resonance can be used for the detection of a product atom. In this case it is shown for the first time that the O((1)D) atom is produced with CO((1)Σ(+)) at 92.21 nm. These results indicate that the VUV laser photodissociation combined with the VUV-PI-VMI detection is a viable method for studying the one-photon photodissociation from the ground state of simple molecules in the extreme ultraviolet and VUV spectral regions.     

Single-photon spectroscopy of singlet sulfur atoms and the autoionization lifetime measurements of the superexcited singlet states

Single-photon excitation spectra from the lowest singlet (1)D(2) level of sulfur atoms were recorded with a tunable vacuum ultraviolet (VUV) radiation source generated by frequency tripling in noble gases. The photolysis of CS(2) at 193 nm was used to produce the singlet S((1)D(2)) sulfur atoms that were then excited to neutral superexcited states with the tunable VUV radiation. These superexcited states undergo autoionization into the first ionization continuum state of S(+)((4)S(3/2) (o))+e(-), which is not directly accessible from the S((1)D(2)) state via an allowed transition. The excitation spectra were recorded by monitoring the S(+) signal in a velocity imaging apparatus while scanning the VUV excitation wavelength. Three new lines were observed in the spectra which have not been previously reported. The full widths at half maximum (FWHM) of each of the observed transitions were determined by fitting the profiles of each absorption resonances with the Fano formula. Autoionization lifetimes tau of these singlet superexcited states were obtained from FWHM using the Uncertainty Principle. Abnormal autoionization lifetimes were found for the 3s(2)3p(3)((2)D(o))nd((1)D(2)) and the 3s(2)3p(3)((2)D(o))ns((1)D(2)) Rydberg series, in which tau(5d) and tau(7s) are shorter than tau(4d) and tau(6s), respectively. This is contrary to the well-known scaling law of tau(n*) proportional, variantn(*3), which should be followed within a series unless there exist perturbations from other series or new channels open up to which some members of the series can decay. Possible perturbations from the nearby triplet series are suspected for causing the broadening of the 5d and 7s levels.     

Photodissociation dynamics of N2O at 130 nm: the N2(A 3Sigmau +,B 3Pig)+O(3PJ = 2,1,0) channels

Oxygen Rydberg time-of-flight spectroscopy was used to study the vacuum ultraviolet photodissociation dynamics of N(2)O near 130 nm. The O((3)P(J)) products were tagged by excitation to high-n Rydberg levels and subsequently field ionized at a detector. In agreement with previous work, we find that O((3)P(J)) formation following excitation to the repulsive N(2)O D((1)Sigma(+)) state produces the first two electronically excited states of the N(2) counterfragment, N(2)(A (3)Sigma(u) (+)) and N(2)(B (3)Pi(g)). The O((3)P(J)) translational energy distribution reveals that the overall branching ratio between N(2)(A (3)Sigma(u) (+)) and N(2)(B (3)Pi(g)) formation is approximately 1.0:1.0 for J = 1 and 2, with slightly less N(2)(B (3)Pi(g)) produced in coincidence with O((3)P(0)). The angular distributions were found to be independent of J and highly anisotropic, with beta = 1.5+/-0.2.     

Fully state-selected VMI study of the near-threshold photodissociation of NO(2): variation of the angular anisotropy parameter

Velocity-map ion imaging (VMI) has been used to study the angular distribution of the NO fragment generated in the photodissociation of NO(2) at a variety of photolysis wavelengths. Images were recorded for the channels NO (2)Pi(1/2) (v = 0, J= 3/2, 11/2 and 21/2) + O ((3)P(2,1)), for excitation energies ranging from the onset (E(avl)/hc = 0 cm(-1)) to E(avl)/hc approximately 900 cm(-1). The angular anisotropy parameter beta was obtained as a function of available energy. Photofragment multiphoton ionization (PHOMPI) spectra were also recorded in the energy range E(avl)/hc = 0-300 cm(-1) for each of these channels. Large fluctuations of beta as a function of E(avl) were found in all observed dissociation channels. These variations are discussed in terms of the lifetimes of the originally photoexcited overlapping resonances in the A(2)B(2) state of NO(2), the dynamics of which are strongly influenced by nonadiabatic coupling with the X[combining tilde](2)A(1) state. The potential use of this photolysis process for production of cold oxygen atoms is discussed.     

Quantum yields for product formation in the 120-133 nm photodissociation of O2

The photodissociation of O(2) in the region from 120-133 nm has been investigated using product imaging. The spectrum in this region is dominated by transitions from the ground state to the first three vibrational levels of the E (3)Sigma(u) (-) state. The O((1)D)+O((3)P) channel is the only product channel observed by product imaging for dissociation at either 124.4 nm or 120.4 nm. The O((1)D(2)) product is aligned in the molecular frame in such a way that its J vector is perpendicular to the relative velocity vector between the O((1)D) and the O((3)P). The variation in the anisotropy of dissociation is approximately predicted by considering transitions on individual lines and then taking into account the coherent excitation of overlapping resonances. At 132.7 nm, both the O((1)D)+O((3)P) and the O((3)P)+O((3)P) channels are observed with branching ratios of 0.40+/-0.08 and 0.60+/-0.09, respectively. At 130.2 nm, the quantum yield for production of O((1)D) is 0.76+/-0.28.     

Dissociation of sulfur dioxide by ultraviolet multiphoton absorption between 224 and 232 nm

Multiphoton excitation and dissociation of SO(2) have been investigated in the wavelength range from 224 to 232 nm. Strong evidence is found for two-photon excitation to the H Rydberg state, followed by dissociation to SO + O and ionization of the SO product by absorption of a third photon. The two-photon excitation is resonantly enhanced via the C (1)B(2) intermediate state, and the two-photon yield spectrum thus bears a strong resemblance to the spectrum of this intermediate. Imaging of the O((3)P(2)), S((1)D(2)), and SO products suggests that, following dissociation of SO(2) from the H state, SO is produced in the A and B electronic states. S((1)D(2)) is produced both from two-photon dissociation of SO(2) to give S((1)D(2)) + O(2) and by single-photon dissociation of SO(+). In the former process, the O(2) is likely formed in all of its lowest three electronic states.     

The photodissociation of NO(2) by visible and ultraviolet light

We present velocity map images of the NO, O((3)P(J)) and O((1)S(0)) photofragments from NO(2) excited in the range 7.6 to 9.0 eV. The molecule was initially pumped with a visible photon between 2.82-2.95 eV (440-420 nm), below the first dissociation threshold. A second ultraviolet laser with photon energies between 4.77 and 6.05 eV (260-205 nm) was used to pump high-lying excited states of neutral NO(2) and/or probe neutral photoproducts. Analysis of the kinetic energy release spectra revealed that the NO photofragments were predominantly formed in their ground electronic state with little kinetic energy. The O((3)P(J)) and O((1)S(0)) kinetic energy distributions were also dominated by kinetically 'cold' fragments. We discuss the possible excitation schemes and conclude that the unstable photoexcited states probed in the experiment were Rydberg states coupled to dissociative valence states. We compare our results with recent time-resolved studies using similar excitation and probe photon energies.     

Iron monoxide photodissociation

The photodissociation of (56)FeO was studied by means of the velocity map imaging technique. A molecular beam of iron atoms and iron monoxide molecules was created using an electrical discharge with an iron electrode in a supersonic expansion of molecular oxygen. The ground state iron atom Fe((5)D(4)) and FeO concentrations in the molecular beam have been estimated. The dissociation energy of the FeO X (5)Delta ground electronic state was found to be D(0) (0)(FeO)=4.18+/-0.01 eV. The effective absorption cross section of FeO at 252.39 nm (vac), leading to the Fe((5)D(4))+O((3)P) dissociation channel, is approximately 1.2 x 10(-18) cm(2). A (1+1) resonantly enhanced multiphoton ionization spectrum of (56)FeO in the region 39 550-39 580 cm(-1) with rotational structure has been observed, but not assigned. Angular distributions of Fe((5)D(4)) and Fe((5)D(3)) products for the channel FeO-->Fe((5)D(4,3))+O((3)P) have been measured at several points in the 210-260 nm laser light wavelength region. The anisotropy parameter varies strongly with wavelength for both channels.     

The photodissociation dynamics of NO2 at 308 nm and of NO2 and N2O4 at 226 nm

Velocity-map ion imaging has been applied to the photodissociation of NO(2) via the first absorption band at 308 nm using (2 + 1) resonantly enhanced multiphoton ionization detection of the atomic O((3)P(J)) products. The resulting ion images have been analyzed to provide information about the speed distribution of the O((3)P(J)) products, the translational anisotropy, and the electronic angular momentum alignment. The atomic speed distributions were used to provide information about the internal quantum-state distribution in the NO coproducts. The data were found to be consistent with an inverted NO vibrational quantum-state distribution, and thereby point to a dynamical, as opposed to a statistical dissociation mechanism subsequent to photodissociation at 308 nm. Surprisingly, at this wavelength the O-atom electronic angular momentum alignment was found to be small. Probe-only ion images obtained under a variety of molecular-beam backing-pressure conditions, and corresponding to O atoms generated in the photodissociation of either the monomer, NO(2), or the dimer, N(2)O(4), at 226 nm, are also reported. For the monomer, where 226 nm corresponds to excitation into the second absorption band, the kinetic-energy release distributions are also found to indicate a strong population inversion in the NO cofragment, and are shown to be remarkably similar to those previously observed in the wavelength range of 193-248 nm. Mechanistic implications of this result are discussed. At 226 nm it has also been possible to observe directly O atoms from the photodissociation of the dimer. The O-atom velocity distribution has been analyzed to provide information about its production mechanism.     

Absolute rate coefficients for the reactions of O2- + N(4S(3/2)) and O2- + O(3P) at 298 K in a selected-ion flow tube instrument

The absolute rate coefficients at 298 K for the reactions of O(2) (-) + N((4)S(3/2)) and O(2) (-) + O((3)P) have been determined in a selected-ion flow tube instrument. O atoms are generated by the quantitative titration of N atoms with NO, where the N atoms are produced by microwave discharge on N(2). The experimental procedure allows for the determination of rate constants for the reaction of the reactant ion with N((4)S(3/2)) and O((3)P). The rate coefficient for O(2) (-) + N is found to be 2.3x10(-10)+/-40% cm(3) molecule(-1) s(-1), a factor of 2 slower than previously determined. In addition, it was found that the reaction proceeds by two different reaction channels to give (1) NO(2)+e(-) and (2) O(-)+NO. The second channel was not reported in the previous study and accounts for ca. 35% of the reaction. An overall rate coefficient of 3.9 x 10(-10) cm(3) molecule(-1) s(-1) was determined for O(2) (-) + O, which is slightly faster than previously reported. Branching ratios for this reaction were determined to be <55%O(3) + e(-) and >45%O(-) + O(2).     

Photodissociation of van der Waals clusters of isoprene with oxygen, C(5)H(8)-O(2), in the wavelength range 213-277 nm

The speed and angular distribution of O atoms arising from the photofragmentation of C(5)H(8)-O(2), the isoprene-oxygen van der Waals complex, in the wavelength region of 213-277 nm has been studied with the use of a two-color dissociation-probe method and the velocity map imaging technique. Dramatic enhancement in the O atoms photo-generation cross section in comparison with the photodissociation of individual O(2) molecules has been observed. Velocity map images of these "enhanced" O atoms consisted of five channels, different in their kinetic energy, angular distribution, and wavelength dependence. Three channels are deduced to be due to the one-quantum excitation of the C(5)H(8)-O(2) complex into the perturbed Herzberg III state ((3)Δ(u)) of O(2). This excitation results in the prompt dissociation of the complex giving rise to products C(5)H(8)+O+O when the energy of exciting quantum is higher than the complex photodissociation threshold, which is found to be 41740 ± 200 cm(-1) (239.6±1.2 nm). This last threshold corresponds to the photodissociation giving rise to an unexcited isoprene molecule. The second channel, with threshold shifted to the blue by 1480 ± 280 cm(-1), corresponds to dissociation with formation of rovibrationally excited isoprene. A third channel was observed at wavelengths up to 243 nm with excitation below the upper photodissociation threshold. This channel is attributed to dissociation with the formation of a bound O atom C(5)H(8)-O(2) + hv → C(5)H(8)-O(2)((3)Δ(u)) → C(5)H(8)O + O and∕or to dissociation of O(2) with borrowing of the lacking energy from incompletely cooled complex internal degrees of freedom C(5)H(8) (?)-O(2) + hv → C(5)H(8) (?)-O(2)((3)Δ(u)) → C(5)H(8) + O + O. The kinetic energy of the O atoms arising in two other observed channels corresponds to O atoms produced by photodissociation of molecular oxygen in the excited a?(1)Δ(g) and b?(1)Σ(g) (+) singlet states as the precursors. This indicates the formation of singlet oxygen O(2)(a?(1)Δ(g)) and O(2)(b?(1)Σ(g) (+)) after excitation of the C(5)H(8)-O(2) complex. Cooperative excitation of the complex with a simultaneous change of the spin of both partners (1)X-(3)O(2) + hν → (3)X-(1)O(2) → (3)X + (1)O(2) is suggested as a source of singlet oxygen O(2)(a?(1)Δ(g)) and O(2)(b?(1)Σ(g) (+)). This cooperative excitation is in agreement with little or no vibrational excitation of O(2)(a?(1)Δ(g)), produced from the C(5)H(8)-O(2) complex as studied in the current paper as well as from the C(3)H(6)-O(2) and CH(3)I-O(2) complexes reported in our previous paper [Baklanov et al., J. Chem. Phys. 126, 124316 (2007)]. The formation of O(2)(a?(1)Δ(g)) from C(5)H(8)-O(2) was observed at λ(pump) = 213-277 nm with the yield going down towards the long wavelength edge of this interval. This spectral profile is interpreted as the red-side wing of the band of a cooperative transition (1)X-(3)O(2) + hν → (3)X(T(2))-(1)O(2)(a?(1)Δ(g)) in the C(5)H(8)-O(2) complex.     

NO+ formation pathways in dissociation of N2O+ ions at the C2Σ+ state revealed from threshold photoelectron-photoion coincidence velocity imaging

Using the novel threshold photoelectron-photoion coincidence (TPEPICO) velocity imaging technique, the dissociative photoionization of N(2)O molecule via the C(2)Σ(+) ionic state has been investigated. Four fragment ions, NO(+), N(2)(+), O(+), and N(+), are observed, respectively, and the NO(+) and N(+) ions are always dominant in the whole excitation energy range of the C(2)Σ(+) ionic state. Subsequently, the TPEPICO three-dimensional time-sliced velocity images of NO(+) dissociated from the vibrational state-selected N(2)O(+)(C(2)Σ(+)) ions have been recorded. Thus the kinetic and internal energy distributions of the NO(+) fragments have been obtained directly as the bimodal distributions, suggesting that the NO(+) fragments are formed via both NO(+)(X(1)Σ(+)) + N((2)P) and NO(+)(X(1)Σ(+)) + N((2)D) dissociation channels. Almost the same vibrational population reversions are identified for both dissociation pathways. Interestingly, the obtained branching ratios of the two channels exhibit some dependence on the excited vibrational mode for N(2)O(+)(C(2)Σ(+)), in which the excited asymmetrical stretching potentially promotes dissociation possibility along the NO(+)(X(1)Σ(+)) + N((2)D) pathway. In addition, the measured anisotropic parameters of NO(+) are close to 0.5, indicating that the C(2)Σ(+) state of N(2)O(+) is fully predissociative, indeed, with a tendency of parallel dissociation, and therefore, the corresponding predissociation mechanisms for the N(2)O(+)(C(2)Σ(+)) ions are depicted.     

Time-sliced velocity-mapped imaging studies of the predissociation of single ro-vibronic energy levels of N2 in the extreme ultraviolet region using vacuum ultraviolet photoionization

The predissociation of N(2) from the rotational levels in the o(1)∏(u) (v(') = 2) and b(') (1)Σ(u) (v(') = 8) bands has been studied in the wavenumber (or energy) range from 109?350 cm(-1) (13.5577 eV) to 109?580 cm(-1) (13.5862 eV) by time-sliced velocity-mapped imaging technique with VUV photoionization detection of the fragments. These levels were excited from the ground state of N(2) (X(1)Σ(g) (+), v(") = 0) levels using an unfocused vacuum ultraviolet (VUV) laser via a one-photon process. The same VUV laser is used to ionize the metastable N ((2)D(o)) produced from the predissociation process and the time-sliced velocity-mapped imaging technique is used to determine their velocity and angular distributions. Two different theoretical methods developed, respectively, by Kim et al. [J. Chem. Phys. 125, 133316 (2006) and Zande [J. Chem. Phys. 107, 9447 (1997)] were used to calculate the anisotropic parameters for the predissociation to the channel N((4)S(o)) + N((2)D(o)) to compare with the observed value for each of the rotational levels. Very good agreement with the experimental results was obtained for both methods. Possible predissociation mechanisms were predicted from the measurements and calculations.     

Time-dependent infrared emission following photodissociation of nitromethane and chloropicrin

Nitromethane (CH(3)NO(2)) and its chlorinated analogue, chloropicrin (CCl(3)NO(2)), were photolyzed at 193, 248, and 266 nm, and the products were observed by time-dependent Fourier transform infrared emission spectroscopy. At 193 and 248 nm, the primary photodissociation pathway for nitromethane was cleavage of the C-N bond to produce CH(3) + NO(2)(A (2)B(2)). At 266 nm, weak emission was observed following photodissociation of nitromethane, but an infrared spectrum could not be obtained. The photodissociation of chloropicrin at 193 nm produced the analogous product channel CCl(3) + NO(2)(A (2)B(2)) in addition to several other product channels. At 248 and 266 nm, only CCl(3) + NO(2)(A (2)B(2)) was observed. The production of phosgene (CCl(2)O) from chloropicrin photodissociation was not observed in this study.     

Communication: branching ratio measurements in the predissociation of 12C16O by time-slice velocity-map ion imaging in the vacuum ultraviolet region

The first direct branching ratio measurement of the three lowest energy dissociation channels of CO that produce C((3)P) + O((3)P), C((1)D) + O((3)P), and C((3)P) + O((1)D) is reported. Rotational resolved carbon ion yield spectra for two Π bands (W(3sσ)(1)Π (v(') = 3) at 108,012.6 cm(-1) and (1)Π(v(') = 2) at 109,017 cm(-1)) and two Σ bands ((4sσ)(1)Σ(+)(v(') = 4) at 109,452 cm(-1) and (4pσ)(1)Σ(+)(v(') = 3) at 109,485 cm(-1)) of CO were obtained. Our measurements show that the branching ratio in this energy region is strongly dependent on the electronic and vibrational energy but it is independent or just weakly dependent on the parity and rotational energy levels. To our knowledge, this is the first time that the triplet channel producing O((1)D) has been experimentally observed and this is also the first time that a direct measurement of the branching ratio for the different channels in the predissociation of CO in this energy region has been made.     

Channel switching effect in photodissociating N2O+ ion at 312.5 nm

A experimental observation is presented on the N2O+ photodissociation process, which exhibits a complete channel switching effect in a narrow energy range. The N2O+ ions, prepared at the X2Pi (000) state by (3+1) multiphoton ionization of neutral N2O molecules at 360.6 nm, were excited to different vibrational levels in the A2Sigma+ state in a wavelength range of 275-328 nm. Based on the estimates of total released kinetic energies from the time-of-flight mass spectrum, it was found that the dissociation pathway of N2O+ (A2Sigma+), NO+ (X1Sigma+) + N(4S) with lower dissociation limit, changes abruptly and completely to NO+ (X1Sigma+) + N(2D) with higher dissociation limit, in a excitation energy range of merely 250 cm(-1) at lambda approximately 312.5 nm. This phenomenon was explained by competition between the two dissociation pathways across the special excitation energy region.     

Comparison of hexamethyldisiloxane dissociation processes in plasma

Different hexamethyldisiloxane (HMDSO) dissociation processes are investigated by means of absorption spectroscopy and mass spectrometry. All of these processes are expected to occur in plasma containing Ar-HMDSO gas mixture. We successively study interactions of the HMDSO molecule with electrons (energy ranges from 15 to 70 eV), with Ar((3)P(2)) metastable species (internal energy 11.55 eV) and with VUV photon (7.3 to 10.79 eV). The studies of HMDSO interactions with Ar((3)P(2)) and VUV photon provide new results concerning the dissociation pathways and the collision cross-sections. In the case of Ar((3)P(2)), the dissociation mechanisms result mainly in Si-C or Si-O bond breaking, producing SiMe(2,1) radicals. Less efficient mechanisms involve also Si-C and Si-O bond breaking producing Me, Si(2)Me(5)O, or SiMe(3), on one hand, and, on the other hand, Si-C and C-H bond breaking producing Si(2)Me(4)OH. In the case of photon interaction, the dissociation process is more selective and mainly produces Si(2)OMe(5) pentadisiloxane and methyl radicals due to Si-C bond breaking. Si-O bond breaking produces also SiMe(3) in a lower concentration. Dissociation cross-section values of HMDSO ranging from σ = 45 × 10(-20) m(2) to 180 × 10(-20) m(2) and from σ = 0.7 × 10(-22) m(2) to 18.3 × 10(-22) m(2), correspond to a global dissociation mechanism by Ar((3)P(2)) collision and to a selective dissociation mechanism (producing Si(2)OMe(5) and Me) by VUV photon interaction, respectively. All results are compared and discussed.     

Ion imaging study of NO3 radical photodissociation dynamics: characterization of multiple reaction pathways

The photodissociation of NO(3) has been studied using velocity map ion imaging. Measurements of the NO(2) + O channel reveal statistical branching ratios of the O((3)P(J)) fine-structure states, isotropic angular distributions, and low product translational energy consistent with barrierless dissociation along the ground state potential surface. There is clear evidence for two distinct pathways to the formation of NO + O(2) products. The dominant pathway (>70% yield) is characterized by vibrationally excited O(2)((3)Σ(g)(-), v = 5-10) and rotationally cold NO((2)Π), while the second pathway is characterized by O(2)((3)Σ(g)(-), v = 0-4) and rotationally hotter NO((2)Π) fragments. We speculate the first pathway has many similarities to the "roaming" dynamics recently implicated in several systems. The rotational angular momentum of the molecular fragments is positively correlated for this channel, suggesting geometric constraints in the dissociation. The second pathway results in almost exclusive formation of NO((2)Π, v = 0). Although product state correlations support dissociation via an as yet unidentified three-center transition state, theoretical confirmation is needed.     

266nm脉冲激光光解基质隔离的cis-(NO)2

NO的氧化是大气化学研究的重要课题．CIS－（NO）。是一氧化氮氧化过程的中间体，对其在低温基质条件下的形成和氧化过程研究前文风已作了报导．H。WhiffS等门曾用中压汞灯作为光解光源（220－320urn），研究了ets－（NO）。在Ar低温基质中的光解，产物为N。O和NZO3．CIS－（NO