Statistical treatment of recordings of spontaneous unit discharges from the ventromedial nucleus and the lateral area of the hypothalamus (the activities in one area being recorded while the other was stimulated) revealed significant reciprocal relations. The concept that glucose-sensitive neurons are present in the ventromedial nucleus was supported by the effects on the spontaneous unit discharges of injecting glucose and other-solutions intravenously.

The two-color (1+1′) threshold photoelectron spectra of naphthalene in a supersonic free jet have been recorded via nine vibronic levels of the S1 electronic state up to about 1420 cm−1 above the S1 band origin. The threshold photoelectron spectra recorded via the S1 band origin and via totally symmetric ag vibronic levels show significant intensity in Δν=+1 transitions in nontotally symmetric vibrations having b1g symmetry indicating that the ionization transition gains significant intensity through a vibronic coupling mechanism between the two lowest doublet cationic states. The strongest departure from the expected Δν=0 propensity in the threshold photoelectron spectra occurs through excitation of the totally symmetric 8 mode having ag symmetry indicating that a considerable displacement occurs along the normal coordinate of this 8 mode upon ionization from the S1 state. The superior resolution of the threshold photoelectron technique over conventional photoelectron methods has allowed accurate values for the fundamental vibrational frequencies of naphthalene in its ground cationic state to be determined and it has also allowed a more rigorous investigation of the vibronic coupling mechanism that occurs between the two lowest doublet cationic states. Moreover, an improved value for the adiabatic ionization energy of naphthalene of 65 687±7 cm−1 (8.1442±0.0009 eV) has been determined.

The vacuum ultra-violet spectra of various mono-substituted benz~les were measured in the wavelength region of 1550 3, to 2200 A in the vapour phase by a recording vacuum ultra-violet spectrophotometer. The compounds studied here are phenols (phenol, anisole, phenetole and thiophenol), halogenobenzenes (fluorobenzene, chlorobenzene, bromobenzene and iodobenzene), and toluene. It was found that four ~ ~r ~ -transition bands appear in the wavelength region of 1550 3, to 3000 ~, for phenol, anisole, phenetole, fluorobenzene, chlorobenzene and bromobenzene, On the other hand, six ~r~ ~ ~ transition bands were found in the same wavelength region for thiophenol and iodobenzene. The absorption spectra of the former group are similar to that of benzene itself. On the other hand, the absorption spectra of the latter group are very different from that of benzene and rather similar to those of the anilines studied in a previous paper. From this point of view, the former group may be regarded as the molecules with weak substituents, and the latter as the molecules with strong substituents.Theoretical studies of rr-electron structures have been carried out with the phenols and halogenobenzenes by considering configurational interactions among the ground, locally excited, and intramolecular charge-transfer configurations. Good agreement was obtained between the experimental and theoretical values for both transition energies and oscillator strengths. It was concluded that the energies of charge-transfer configurations have a great effect upon the absorption spectra of the mono-substituted benzene molecules. That is to say, the charge-transfer configurations lie intermediate between the locally excited configurations for the molecules with strong substituents, while for the molecules with weak substituents they have higher energies than the locally excited configurations. Intramolecular chargetransfer bands were observed for the molecules with strong substituents.The electron affinity of benzene was determined to be -1"1 +0"3 ev from the energy of the charge-transfer configuration estimated in such a way as to explain as well as possible the observed absorption spectra of the mono-substituted benzenes under consideration.

Measurements of mass-selected ion-current and threshold photoelectron spectra of jet-cooled aniline–Arn van der Waals complexes (n=1 and 2) have been carried out with a two-color resonantly enhanced multiphoton ionization (REMPI) technique using a high-resolution threshold photoelectron analyzer developed in this laboratory. From our (1+1′) REMPI experiments via the respective excited S1 states, we have obtained photoelectron spectra with well-resolved vibrational progressions due to ‘‘low-frequency van der Waals modes’’ of the cations; νvdW=16 cm−1 (n=1) and νvdW=11 cm−1 (n=2). From Franck–Condon calculations, we have assigned these low-frequency vibrations to the ‘‘van der Waals bending’’ of the cations. We have also found that the angles of the van der Waals bonds in the cations are changed by 8.2 (n=1) and 8.8 (n=2) degrees with respect to the S1 states. The adiabatic ionization potentials (Ia) of aniline and the aniline–Arn complexes (n=1 and 2) have been determined as 62 268±4 cm−1 (aniline), 62 157±4 cm−1 (n=1), and 62 049±4 cm−1 (n=2). Their shifts ΔIa are 111 cm−1 (n=1) and 219 cm−1 (n=2) with respect to aniline. Spectral shifts due to complex formation have been observed for a total of 13 ring modes of the cations.

Benzonitrile and its van der Waals (vdW) complexes with argon (benzonitrile-Ar and benzonitrile-Ar 2 ) have been studied in supersonic jets by two-color zero-kinetic-energy (ZEKE) photoelectron spectroscopy for the first time. From the (1+1′) ZEKE photoelectron spectra obtained via the first electronic excited state (S 1 ), we have determined adiabatic ionization potentials as I a (benzonitrile) ) 78 490 ( 2 cm -1 (9.7315 ( 0.0002 eV), I a (benzonitrile-Ar) ) 78 241 ( 4 cm -1 (9.7007 ( 0.0005 eV), and I a (benzonitrile-Ar 2 ) ) 78 007 ( 4 cm -1 (9.6716 ( 0.0005 eV). These values indicate that the decrease in ionization potential due to the complex formation (∆I a ) -249 and -483 cm -1 , respectively) is very large compared with other monosubstituted benzenes. Eleven low-frequency vibrational modes of the bare benzonitrile cation below 1300 cm -1 have been identified in the ZEKE photoelectron spectra. The in-plane CsCtN bending mode (33 + ) and the out-of-plane C-C-C bending mode (22 + ) have been clearly identified from the ZEKE photoelectron spectra obtained via the S 1 vibrational levels 33 1 and 22 2 , respectively. Furthermore, in the benzonitrile-Ar and -Ar 2 spectra, we have observed well-resolved vibrational progressions with very low frequencies of 12 and 9 cm -1 , respectively, which may be assigned to the vdW bending mode (b x + ) and the vdW symmetric bending mode (b xs + ) along the substituent axis, respectively.

The vacuum ultraviolet absorption spectra of anilne, N-methylaniline, N-ethylaniline, N,N-dimethylaniline, N,N-diethylaniline and N-n-butylaniline have been measured in the vapor phase by a recording vacuum ultraviolet spectrophotometer, with which the absorption measurements have been extended down to 1500 Å. Some new bands have been found in the vacuum ultraviolet region, and in total five π→π* transtion bands with molar extinction coefficients larger than 1500 have been observed commonly for the anilines. In order to clarify the nature of these bands, a theoretical treatment has been made by considering the configuration interaction among the ground, locally excited and charge-transfer configrations. An excellent agreement has been obtained between the experimental and the calculated result. It has been concluded the the anilines studied here exhibit intramolecular charge-transfer bands characteristic if the electron trasfer interaction between the substituent and benzene ring.

Articles you may be interested inTwo-dimensional laser induced fluorescence spectroscopy of van der Waals complexes: Fluorobenzene-Ar n (n = 1,2) J. Chem. Phys. 136, 134309 (2012); 10.1063/1.3697474 X-ray photoelectron spectroscopy study of polyimide thin films with Ar cluster ion depth profiling J. Vac. Sci. Technol. A 28, L1 (2010); 10.1116/1.3336242Low lying electronic states of rare gas-oxide anions: Photoelectron spectroscopy of complexes of O − with Ar, Kr, Xe, and N 2 Fragmentation energetics and dynamics of fluorobenzeneAr n (n=1-3) clusters studied by mass analyzed threshold ionization spectroscopy In this work, the molecules styrene (ST) and phenylacetylene (PA), as well as their argon complexes ST -Ar and PA-Ar, have been investigated with (1 + 1') resonance enhanced multiphoton ionization (REMPI) threshold photoelectron spectroscopy (TES). The first adiabatic ionization energies of ST, PA, ST -Ar, and PA-Ar have been measured as 68 267 ± 5, 71175±5, 68 151 ±5, and 71 027±5 cm-I , respectively. For both ST-Ar and PA-Ar, the first photoelectron band shows structure in the lowest frequency van der Waals (vdW) bending mode in the ground ionic state, with VydW being measured as 15 cm-I in each case. For each molecule excitation to a particular vibrational level of the S I state followed by ionization, allows structure in that mode to be observed in the threshold photoelectron spectrum. This has been achieved for three modes in both styrene and phenylacetylene. The experimental ionic vibrational frequencies thus obtained, have been compared with those known for the So and S I states.a)IMS Visiting Fellow. Permanent address:

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