A 3.0 µm Pixels and 1.5 µm Pixels Combined Complementary Metal-Oxide Semiconductor Image Sensor for High Dynamic Range Vision beyond 106 dB.

We propose a new concept image sensor suitable for viewing and sensing applications. This is a report of a CMOS image sensor with a pixel architecture consisting of a 1.5 µm pixel with four-floating-diffusions-shared pixel structures and a 3.0 µm pixel with an in-pixel capacitor. These pixels are four small quadrate pixels and one big square pixel, also called quadrate-square pixels. They are arranged in a staggered pitch array. The 1.5 µm pixel pitch allows for a resolution high enough to recognize distant road signs. The 3 µm pixel with intra-pixel capacitance provides two types of signal outputs: a low-noise signal with high conversion efficiency and a highly saturated signal output, resulting in a high dynamic range (HDR). Two types of signals with long exposure times are read out from the vertical pixel, and four types of signals are read out from the horizontal pixel. In addition, two signals with short exposure times are read out again from the square pixel. A total of eight different signals are read out. This allows two rows to be read out simultaneously while reducing motion blur. This architecture achieves both an HDR of 106 dB and LED flicker mitigation (LFM), as well as being motion-artifact-free and motion-blur-less. As a result, moving subjects can be accurately recognized and detected with good color reproducibility in any lighting environment. This allows a single sensor to deliver the performance required for viewing and sensing applications.

Electronic and vibrational structures in the S0 and S1 states of coronene.

We observed the fluorescence excitation spectra and dispersed fluorescence spectra of jet-cooled coronene-h12 and coronene-d12. We analyzed the vibronic structures, assuming a planar and sixfold symmetric molecular structure (D6h). The S1 state was identified to be B2u1. The S1B2u1←S0A1g1 transition is symmetry forbidden, so the 000 band is missing in the fluorescence excitation spectrum. We found a number of vibronic bands that were assigned to the e2g fundamental bands and their combination bands with totally symmetric a1g vibrations. This spectral feature is similar to that of benzene although several strong e2g bands are seen in coronene. The band shape (rotational envelope) was significantly different in each e2g mode. It was shown that degenerate rotational levels were shifted and split by the Coriolis interaction. We calculated the Coriolis parameter using the molecular structure in the S1 state and the normal coordinate of each e2g vibrational mode, which were obtained by theoretical calculations. The calculated band shapes well reproduced the observed ones, suggesting that the isolated coronene molecule has D6h symmetry.

Spectroscopic study on deuterated benzenes. III. Vibronic structure and dynamics in the S(1) state.

We observed the fluorescence excitation spectra and mass-selected resonance enhanced multiphoton ionization (REMPI) excitation spectra for the 6(0)(1), 6(0)(1)1(0)(1), and 6(0)(1)1(0)(2) bands of the S1←S0 transition of jet-cooled deuterated benzene and assigned the vibronic bands of C6D6 and C6HD5. The 6(0)(1)1(0)(n) (n = 0, 1, 2) and 0(0)(0) transition energies were found to be dependent only on the number of D atoms (ND), which was reflected by the zero-point energy of each H/D isotopomer. In some isotopomers some bands, such as those of out-of-plane vibrations mixed with 6(1)1(n), make the spectra complex. These included the 6(1)10(2)1(n) level or combination bands with ν12 which are allowed because of reduced molecular symmetry. From the lifetime measurements of each vibronic band, some enhancement of the nonradiative intramolecular vibrational redistribution (IVR) process was observed. It was also found that the threshold excess energy of "channel three" was higher than the 6(1)1(2) levels, which were similar for all the H/D isotopomers. We suggest that the channel three nonradiative process could be caused mainly by in-plane processes such as IVR and internal conversion at the high vibrational levels in the S1 state of benzene, although the out-of-plane vibrations might contribute to some degree.

S1 and S2 states of linear and zigzag cata-condensed hydrocarbons.

We investigated the S1 and S2 states of linear and zigzag cata-condensed hydrocarbons on the basis of the results of jet spectroscopy and theoretical calculations. The S1 states of anthracene and tetracene are represented by the HOMO → LUMO configuration (Φ(A)), whereas those of phenanthrene and chrysene are represented by HOMO-1 → LUMO and HOMO → LUMO+1 configurations (Φ(B)). We found that the fluorescence lifetime varied with different vibronic levels in the S1 states of linear cata-condensed hydrocarbons due to the mode-selective internal conversion to the S0 state. This selectivity is likely to be seen in the S1 Φ(A) state of the D(2h) molecule.

Jet spectroscopy of buckybowl: electronic and vibrational structures in the S0 and S1 states of triphenylene and sumanene.

Sumanene is a typical buckybowl molecule with C3v symmetry. We observed a fluorescence excitation spectrum and a dispersed fluorescence spectrum of sumanene in a supersonic jet. Bowl effects were clarified by comparing the spectra with those of triphenylene (D3h symmetry), which is a planar prototype of nonplanar sumanene. The S1 (1)A1 ← S0 (1)A1 transition is symmetry allowed. We found the 0(0)(0) band in the fluorescence excitation spectrum at 357.78 nm; this band was missing in the forbidden S1 (1)A1(') ← S0 (1)A1(') transition of triphenylene. The transition moment was shown to be along the oblate symmetric top axis (out of plane) by the observed rotational contour. A large number of vibronic bands were observed, unlike in triphenylene. Some were considered to be out-of-plane vibrational modes, which lead to a bowl-to-bowl inversion reaction assisted by in-plane vibrations. We found that the vibronic bands were markedly weak in the high energy region of triphenylene-d12. This indicates that the fluorescence quantum yield is very low at the high vibrational levels in the S1 state due to the rapid radiationless transition. The main process is considered to be internal conversion to the S0 state. The nonplanar structural distortion may also enhance radiationless transitions. We could not, however, observe weakening of the vibronic bands in the fluorescence excitation spectrum of sumanene.

Electronic, vibrational, and rotational structures in the S0 1A1 and S1 1A1 states of phenanthrene.

Electronic and vibrational structures in the S(0) (1)A(1) and S(1) (1)A(1) states of jet-cooled phenanthrene-h(10) and phenanthrene-d(10) were analyzed by high-resolution spectroscopy using a tunable nanosecond pulsed laser. The normal vibrational energies and molecular structures were estimated by ab initio calculations with geometry optimization in order to carry out a normal-mode analysis of observed vibronic bands. The rotational structure was analyzed by ultrahigh-resolution spectroscopy using a continuous-wave single-mode laser. It has been demonstrated that the stable geometrical structure is markedly changed upon the S(1) ← S(0) electronic excitation. Nonradiative internal conversion in the S(1) state is expected to be enhanced by this structural change. The observed fluorescence lifetime has been found to be much shorter than the calculated radiative lifetime, indicating that the fluorescence quantum yield is low. The lifetime of phenanthrene-d(10) is longer than that of phenanthrene-h(10) (normal deuterium effect). This fact is in contrast with anthracene, which is a structural isomer of phenanthrene. The lifetime at the S(1) zero-vibrational level of anthracene-d(10) is much shorter than that of anthracene-h(10) (inverse deuterium effect). In phenanthrene, the lifetime becomes monotonically shorter as the vibrational energy increases for both isotopical molecules without marked vibrational dependence. The vibrational structure of the S(0) state is considered to be homogeneous and quasi-continuous (statistical limit) in the S(1) energy region.

Vibrational and rotational structure and excited-state dynamics of pyrene.

Vibrational level structure in the S(0) (1)A(g) and S(1) (1)B(3u) states of pyrene was investigated through analysis of fluorescence excitation spectra and dispersed fluorescence spectra for single vibronic level excitation in a supersonic jet and through referring to the results of ab initio theoretical calculation. The vibrational energies are very similar in the both states. We found broad spectral feature in the dispersed fluorescence spectrum for single vibronic level excitation with an excess energy of 730 cm(-1). This indicates that intramolecular vibrational redistribution efficiently occurs at small amounts of excess energy in the S(1) (1)B(3u) state of pyrene. We have also observed a rotationally resolved ultrahigh-resolution spectrum of the 0(0) (0) band. Rotational constants have been determined and it has been shown that the pyrene molecule is planar in both the S(0) and S(1) states, and that its geometrical structure does not change significantly upon electronic excitation. Broadening of rotational lines with the magnetic field by the Zeeman splitting of M(J) levels was very small, indicating that intersystem crossing to the triplet state is minimal. The long fluorescence lifetime indicates that internal conversion to the S(0) state is also slow. We conclude that the similarity of pyrene's molecular structure and potential energy curve in its S(0) and S(1) states is the main cause of the slow radiationless transitions.

High-resolution spectroscopy of weak and short-lived bands of the S(1) 1B(3u) <-- S(0) 1A(g) transition of naphthalene.

Rotationally resolved high-resolution spectra and fluorescence decay curves have been observed for weak and short-lived vibronic bands of the S(1) (1)B(3u) <-- S(0) (1)A(g) transition of naphthalene. Fluorescence lifetime of the vibronic band with an excess energy of 1390 cm(-1) (0(0)(0) + 1390 cm(-1) band) is remarkably shorter than that of other bands. Zeeman splitting of rotational lines is very small, so that the main radiationless process is not intersystem crossing to the triplet state but internal conversion to the ground state. The lifetime is thought to be governed by the strength of vibronic coupling between vibrational levels of the S(0) and S(1) states. As for the 0(0)(0) + 2570 cm(-1) band, energy shifts were found in only a few rotational levels although the excess energy was higher than the threshold of intramolecular vibrational redistribution. We conclude that all of the rotational levels are mixed with other vibrational levels. The 0(0)(0) + 3068 cm(-1) band spectrum is fairly complicated with numerous rotational lines, which is attributed to strong vibronic coupling with the S(2) (1)B(2u) state.

CH3 internal rotation in the S0 and S1 states of 9-methylanthracene.

Fluorescence excitation spectra and dispersed fluorescence spectra of jet-cooled 9-methylanthracene-h12 and -d12 (9MA-h12 and 9MA-d12) have been observed, and the energy levels of methyl internal rotation (CH3 torsion) in the S0 and S1 states have been analyzed. The molecular symmetry of 9MA is the same as that of toluene (G12). Because of two-fold symmetry in the pi system, the potential curve has six-fold barriers to CH3 rotation. In toluene, the barrier height to CH3 rotation V6 is very small, nearly free rotation. As for 9MA-h12, we could fit the level energies by potential curves with the barrier heights of V6(S0) = 118 cm(-1) and V6(S1) = 33 cm(-1). These barrier heights are remarkably larger than those of toluene and are attributed to hyperconjugation between the pi orbitals and methyl group. The dispersed fluorescence spectrum showed broad emission for the excitation of 0(0)(0) + 386 cm(-1) band, indicating that intramolecular vibrational redistribution efficiently occurs, even in the vibronic level of low excess energy of the isolated 9MA molecule.

Vibronic structure in the S1-S0 transition of jet-cooled dibenzofuran.

Fluorescence excitation spectra of dibenzofuran in a supersonic jet are observed and the vibronic structure is analyzed for the S(1) (1)A(1) (pipi) and S(0) states. An observation of the rotational envelopes reveals that the band is a B-type band. However, it is shown that most of the strong vibronic bands are A-type bands. The intensity arises from vibronic coupling with the S(2) (1)B(2) state. We find a broad emission in the dispersed fluorescence spectrum for the excitation of the high vibrational levels in the S(1) state. This indicates that intramolecular vibrational redistribution (IVR) occurs efficiently in the isolated dibenzofuran molecule.