Objective Fluid creep in patients recovering from acute burns still exists, despite the use of a more treatment conservative approach. Most of our severe burn patients develop fluid overload and body weight increase after acute fluid resuscitation. How to quickly return patients to their pre-injury body weight is an important issue. Methods Right after acute fluid resuscitation, we applied a “total fluid requirement” volume (usually 1/2 to 2/3 of initial 24 hour volume) and strictly monitored patients' hourly urine (between 0.5-1 ml/kg/hr). Patients' responses (body weight, enteric feeding amount, pulmonary condition, etc.) were also closely monitored and frequent adjustments of fluid volume administration were performed simultaneously. Results Most patients regained their pre-injury body weight within 2-3 weeks. Enteric feeding also improved markedly. No patients had severe oedema-related complications. Conclusions Stricter fluid administration after acute burn fluid resuscitation is advised for allowing patients to reduce body weight to their pre-injury weight or at least close to it. We use pre-injury body weight, enteric feeding and urine output as our guides. (Hong Kong j.emerg.med. 2014;21:222-229)

The red and orange emitters (ANA-1-3) consisting of a 4-amino-1,8-naphthalic anhydride group were synthesized. The lowest absorption band of these ANA molecules centered at approximately 450 nm is assigned to be a charge-transfer transition with emission at 514-536 nm in nonpolar solvents such as n-hexane and at approximately 590-640 nm in polar solvents such as THF and CH(2)Cl(2) and in the solid states. Emission lifetimes are measured with time-correlated single photon counting. Shorter lifetimes are observed for the ANA molecules when dissolved in polar solvents compared with those in nonpolar solvents. Strong dipole-dipole interaction of ANA molecules with solvents is indicated. At high concentrations the measured emission lifetimes, generally shortened from self-quenching, are found to remain about the same order of magnitude in ANAs. This implies that the exciton states of aggregates are formed and they exhibit a relatively long lifetime. Crystallographic data of 4-(phenyl antracen-9-yl) (ANA-2) and 4-(phenyl-2-naphthyl) amino-1,8-naphthalic anhydrides (ANA-3) show that the molecules exist as dimeric structures with antiparallel head-to-tail stacking of naphthalic anhydride planes in addition to other pi-pi stacking. The strong dipole-dipole interactions and the pi-pi stacking account for the observed red-shifted emissions of ANAs in the powders. For films prepared from vacuum sublimation, a structure similar to that in the crystal but with less crystalline order is expected based on the emission wavelength. Several electroluminescent devices based on these ANAs are reported here; they emit orange-red light at 602-628 nm with high brightness and steady external quantum efficiency.

Fluorescence decays of benzosultine and naphthosultine excited at 263nm are detected with time-correlated single-photon counting (TCSPC). Both molecules display biexponential decay with a rapid component (time constants 90 and 350ps for benzosultine and naphthosultine, respectively) assigned to an electronically excited state Sn at high energy and the slow one (constants 7.5 and 9.0ns for benzosultine and naphthosultine, respectively) to the S1 state. Dissociation of both molecules was investigated with nanosecond laser flash photolysis combined with transient absorption to detect the intermediates and products. With excitation at 266nm, benzosultine yields a transient with absorption maximum at λmax = 370nm; this transient has a short-lived component with lifetime around 1μs and a long-lived component. Both components are insensitive to molecular oxygen. The short-lived component is tentatively assigned to the dissociation intermediate and the long-lived to be singlet o-benzoquinodimethane (o-BQDM). Photolysis of naphthosultine yields two transient species with absorption at λmax = 420 and 520nm; we assign the former band to triplet–triplet absorption of naphthosultine and the latter to absorption by the product singlet o-naphthoquinodimethane. Optimal geometries, energetics, and vertical transitions of benzosultine, naphthosultine, o-benzoquinodimethane, and o-naphthoquinodimethane are calculated using methods based on density-functional theory (B3LYP/6-311++G**) and time-dependent density-functional theory (TD-DFT). The results of these calculations imply that the ground electronic state of these two o-quinodimethanes (o-QDM) is singlet with a structure of diene form. Their triplet states display a biradical structure. The energy separation between singlet and triplet states of o-benzoquinodimethane is calculated to be ca. 93.6kJ/mol, but for o-naphthoquinodimethane, it is only ca. 27.8kJ/mol.

Femtosecond time-resolved absorption measurements on Ir complexes are performed. On excitation at wavelength 400 nm, singlet metal-to-ligand charge-transfer (MLCT) states are excited. On probing at 580 nm, a transient absorption appears with time constant 70–100 fs. This transient state rising rapidly but decaying very slowly is assigned to be the lowest triplet MLCT state. Accordingly intersystem crossing in these Ir complexes is rapid. Measured with a nanosecond laser, emission from the lowest triplet MLCT state decays with lifetimes 1.55, 1.65 and 1.7 μs for Ir(ppy)3, Ir(DBQ)2(acac) and Ir(MDQ)2(acac), respectively. On 266-nm excitation with a femtosecond laser, high-energy states with mostly π–π* character (ligand-centered states) are accessed; they relax to the lowest triplet MLCT state with time constant 100–350 fs. The efficient flow of energy from high-energy electronic states to 3MLCT results in high quantum yield in electroluminescent phosphorescence in organic light-emitting diodes.

The G6 group-theoretical high-barrier formalism developed previously for internally rotating and inverting CH3NHD is used to interpret the abnormal torsional splittings in the S1 state of acetaldehyde for levels 14(0-)15(0), 14(0-)15(1), and 14(0-)15(2), where 14(0-) denotes the upper inversion tunneling component of the aldehyde hydrogen and 15 denotes the methyl torsional vibration. This formalism, derived using an extended permutation-inversion group G6m, treats simultaneously methyl torsional tunneling, aldehyde-hydrogen inversion tunneling and overall rotation. Fits to the rotational states of the four pairs of inversion-torsion vibrational levels (14(0+)15(0A,E), 14(0-)15(0A,E)), (14(0+)15(1A,E), 14(0-)15(1A,E)), (14(0+)15(2A,E), 14(0-)15(2A,E)), and (14(0+)15(3A,E), 14(0-)15(3A,E)) are performed, giving root-mean-square deviations of 0.003, 0.004, 0.004, and 0.004 cm(-1), respectively, which are nearly equal to the experimental uncertainty of 0.003 cm(-1). For torsional levels lying near the top of the torsional barrier, this theoretical model, after including higher-order terms, provides satisfactory fits to the experimental data. The partially anomalous K-doublet structure of the S1 state, which deviates from that in a simple torsion-rotation molecule, is fitted using this formalism and is shown to arise from coupling of torsion and rotation motion with the aldehyde-hydrogen inversion.

The dynamics of photodissociation of glyoxal (HOC–COH) near the dissociation threshold on the triplet manifold are studied through measurement of distributions of nascent fragment HCO in various internal states. Three rotational levels 101*, 413*, and 321*+322* of vibrational state U (excitation wavelength ∼394.4 nm, origin at 25 331.865 cm−1) of glyoxal in state à 1Au and two other vibrational states at excitation wavelengths 390.33 and 382.65 nm are selected to produce fragment HCO. By means of fluorescence in the transition B̃ 2A′–X̃ 2A′ of HCO, we determined the relative populations of internal states of that fragment. Rotational states of product HCO up to N=26 and K=2 are populated, and bimodal distributions of these rotational states are observed for the photolysis wavelengths used in this work. The high rotational part of the distribution with average energy near values calculated on the basis of the statistical model—phase-space theory is assigned to arise from glyoxal on its S0 surface, and the low rotational part from the T1 surface with an exit barrier. After photolysis near the threshold region on the triplet surface, HCO arising from the T1 state appears to be a major component of products because these rotational levels 101*, 413*, and 32* of U state selected are gateway states with an enhanced rate of intersystem crossing.

The effect of collision on quantum beat is studied theoretically by applying the density matrix method. As an application of this theory, we analyze the experimentally observed quantum beat appearing in the time-resolved fluorescence profiles of biacetyl. In order to explain complicated fluorescence beating patterns, we present a three-state model and several important molecular properties are mapped onto this model. We also investigate how quantum beat patterns appear as a function of the number of the triplet states that are involved in the interaction with the singlet state.

Fluorescence excitation spectra for transition à 1Au–X̃ 1Ag of trans-glyoxal in a supersonic jet were recorded with laser excitation in a wavelength region near 395 nm. With resolution 0.04 cm−1, most lines in these spectra are resolved and are assigned rotationally; of six bands assigned, three have c-type rotational structure, and another three have types a/b hybrid, a and b. Fluorescence decays with quantum beats, resulting from coherent excitation of S1 and T1 states, are observed for most rotational levels in this region. In spectra transformed to the frequency domain for these decays, the widths are larger than those obtained at low excitation energy. The widths from nonzero frequency lines, reflecting mostly the triplet character, indicate that the triplet state is dissociating. Fluorescence spectra of fragment HCO confirm that the dissociation channel correlated to the triplet surface of glyoxal involves formation of radical products. From an abrupt decrease of lifetime of the triplet state and onset of disappearance of fluorescence of glyoxal, the threshold for formation of fragment HCO from trans-glyoxal is determined to be 394.4 nm. With data for heat of formation this threshold yields an exit barrier 2.5±0.5 kcal/mol. Signal of HCO for wavelengths greater than the threshold position up to 400.5 nm is observed and is assigned to arise from the S0 surface. Rotationally state-resolved appearance rates of HCO for a vibrational state near the dissociation threshold are measured. Relative to lifetimes obtained from eigenstates in the quantum-beat data, the appearance time of product HCO reflecting the overall depletion of glyoxal is on average longer. Some observed gateway states with enhanced yields of HCO are considered to result from strong singlet–triplet interaction.

The effects of collisions and magnetic fields on quantum beat are treated by the density matrix method. Some experimental quantum beat results of biacetyl in the presence of collisions are presented and theoretically analysed. It is shown that in this case not only pure dephasing but also pressure dependent inherent decay rate constants can be observed; this implies that the Schrödinger method cannot be employed for this case. The magnetic field effect on quantum beat is examined also and it is shown that for the biacetyl molecule magnetic splitting can be observed even in fields of a few gauss.

Decays of individual rovibronic levels of trans-glyoxal in its first excited singlet state are investigated in supersonic-jet conditions. Several rotational levels display oscillatory decay from coherent excitation of superposition of singlet and triplet states. Analysis yields a lower bound for the state-dependent coupling matrix elements υST=0.08–62 MHz for the S1–T1 interaction. These matrix elements of the lowest singlet and triplet states show no simple systematic dependence on vibrational states, but the singlet state at greater K quantum number couples to a few triplet states with υST larger than for the state at lower K. The complex beat pattern is explored on varying the polarization of the laser beam relative to an external magnetic field. For state NKaKc=312 at excitation energy 25 254.36 cm−1, the Landé g factor of its coupling triplet hyperfine levels is estimated. From comparison with the theoretical g value for the Hund’s case (b), we found that for this state rotational angular momentum is conserved during singlet–triplet coupling. Irregular MF splittings and correlated beating frequencies resulting from resonance coupling between the singlet and triplet states are observed in the Fourier-transform spectra under the weak magnetic field condition.

In the fluorescence excitation spectrum of acetaldehyde cooled in a supersonic jet, we performed a full rotational analysis of combination bands 10011400+150n and 10011400−150n, n=0–4 in the system A1A″–X1A′. The vibrational frequency of the C–C–O bending mode is determined to be ν10′=373.163(3) cm−1. The rotational structures of combination bands 10011400+1502, 10011400−1502, 10011400+1503, and 10011400−1504 resemble the structures of 1400+1502, 1400−1502, 1400+1503, and 1400−1504, respectively, but the intense E lines observed for 1400−1503 are not found in 10011400−1503. Torsional spacings observed in the C–C–O bend series are slightly smaller than those in the pure torsional series 140+ and 140−; these result from a decreased torsional barrier due to the C–C–O bending motion. Inversion spacings exhibit a pattern similar to those in the series 140+ and 140−. Reversed abnormal torsional sublevel A/E splittings are found for states n=0–2 of the 101140− series, similar to those in the 140− series. For st...

The fluorescence excitation spectrum of acetaldehyde in its transition à 1A″–X̃ 1A′ is analyzed for torsional states above the barrier. States with torsional vibrational quantum numbers vt=5A, 5E, and 6A at term energies 660–927 cm−1 are assigned. This region is 100–370 cm−1 above the torsional barrier. These states lie between the limits of torsional vibrational motion and free internal rotor motion, so that the close-lying 5A2 and 6A1 states mix for K>0, and K states in the E sublevel are widely split. From an analysis of calculated eigenfunctions, the composition of K=1 sublevels reaches nearly equal proportions of odd (A2) and even (A1) torsional wave functions when levels exceed the top of the torsional barrier, whereas the K=1 eigenfunctions of vt=4A1 lying near consists of mostly even (A1) functions. Avoided crossings with ΔK=0 and Δm=0 mod 3 selection rules are observed between K=2, E sublevels of 140+154 and 140+155 and between K=2, E sublevels of 140−154 and 140−155. The K energy-level structure of 140+155 deviates significantly from the expected parabolic shape. The K structures and the K state at the lowest energy differ appreciably for the two inversion doublets 140+ and 140−.

Fluorescence of transition à 1Au−X̃ 1Ag of trans-glyoxal in a supersonic jet is recorded with laser excitation in the wavelength region 393–417 nm. Full rotational analysis is performed for nine bands in a region 395–410 nm. Fluorescence decays with quantum beats from several rovibrational levels in à 1Au of glyoxal are detected. As lines in Fourier-transform spectra of those decay curves split on application of an external magnetic field, this oscillatory behavior results from coherent excitation of mixed S1 and T1 states. On excitation with high energy, those lines become broadened as the lifetime of the T1 state decreases because of coupling to a dissociation continuum. An abrupt increase of linewidth in transformed spectra at 25 350 cm−1 (394.5 nm) indicates that this position corresponds to a threshold for dissociation. For excitation energy greater than 25 450 cm−1, most observed decay curves of fluorescence emission display biexponential behavior. The decay of the fast component of the biexponential curve corresponds to intersystem crossing and the slow component to decay of those eigenstates. For energies exceeding 25 550 cm−1, the slow component diminishes, to yield nearly single exponential decay, indicating that the rate of dissociation is greater than that of intersystem crossing. Results of these quantum-beat experiments imply a new dissociation pathway from the triplet surface.

We study the applicability of femtosecond time-resolved photoelectron spectroscopy to the study of substituent effects in molecular electronic relaxation dynamics using a series of monosubstituted benzenes as model compounds. Three basic types of electronic substituents were used: C=C (styrene), C=O (benzaldehyde), and CdropC (phenylacetylene). In addition, the effects of the rigidity and vibrational density of states of the substituent were investigated via both methyl (alpha-methylstyrene, acetophenone) and alkyl ring (indene) substitution. Femtosecond excitation to the second pipi* state leads, upon time-delayed ionization, to two distinct photoelectron bands having different decay constants. Variation of the ionization laser frequency had no effect on the photoelectron band shapes or lifetimes, indicating that autoionization from super-excited states played no discernible role. From assignment of the energy-resolved photoelectron spectra, a fast decaying component was attributed to electronic relaxation of the second pipi* state, a slower decaying component to the first pipi* state. Very fast electronic relaxation constants (< 100 fs) for the second pipi* states were observed for all molecules studied and are explained by relaxation to the first pipi* via a conical intersection near the planar minimum. Although a "floppy" methyl substitution (a-methylstyrene, acetophenone) leads as expected to even faster second pipi* decay rates, a rigid ring substitution (indene) has no discernible effect. The much slower electronic relaxation constants of the first pipi* states for styrene and phenylacetylene are very similar to those of benzene in its first pipi* state, at the same amount of vibrational energy. By contrast, the lifetime of the first pipi* state of indene was much longer, attributed to its rigid structure. The second pipi* state of benzaldehyde has a short lifetime, similar to the other derivatives. However, the relaxation of its first pipi* state is orders of magnitude faster than that of the non-carbonyl compounds, due to the well-known presence of a lower lying pipi* state. Methylation (acetophenone) leads to still faster first pipi* state relaxation rates. These results fit very well with the current understanding of aromatic photophysics, demonstrating that time-resolved photoelectron spectroscopy provides for a facile, accurate and direct means of studying electronic relaxation dynamics in a wide range of molecular systems.

Following photodissociation of vinyl chloride at 193 nm, fully resolved vibration-rotational emission spectra of HCl in the spectral region 2000–3310 cm−1 are temporally resolved with a step-scan Fourier-transform spectrometer. Under improved resolution and sensitivity, emission from HCl up to v=7 is observed, with J>32 (limited by overlap at the band head) for v=1–3. All vibrational levels show bimodal rotational distribution with one component corresponding to ∼500 K and another corresponding to ∼9500 K for v⩽4. Vibrational distributions of HCl for both components are determined; the low-J component exhibits inverted vibrational population of HCl. Statistical models are suitable for three-center (α, α) elimination of HCl because of the loose transition state and a small exit barrier for this channel; predicted internal energy distributions of HCl are consistent but slightly less than those observed for the high-J component. Impulse models considering geometries and displacement vectors of transition states during bond breaking predict substantial rotational excitation for three-center elimination of HCl but little rotational excitation for four-center (α, β) elimination; observed internal energy of the low-J component is consistent with that predicted for the four-center elimination channel. Rate coefficients 33.8 and 4.9×1011 s−1 for unimolecular decomposition predicted for three-center and four-center elimination channels, respectively, based on Rice-Ramsberger-Kassel-Marcus theory are consistent with the branching ratio of 0.81:0.19 determined by counting vibrational distribution of HCl to v⩽6 for high-J and low-J components. Hence we conclude that observed high-J and low-J components correspond to HCl (v, J) produced from three-center and four-center elimination channels, respectively.

ClCO was produced as a reaction intermediate after irradiation of a flowing mixture of Cl2/CO/Ar at 355 nm. A step-scan time-resolved Fourier-transform infrared spectrometer operated in absorption mode was employed to detect ClCO. A transient spectrum at a resolution of 0.13cm−1 partially reveals rotational structure with the Q-branch peaked at 1884.59cm−1; the transition is associated with the C–O stretching (ν1) mode of ClCO. Calculations with density-functional theory (B3LYP/aug-cc-pVTZ) predict the geometry, vibrational and rotational parameters of 35ClCO and 37ClCO. A simulated absorption spectrum based on these parameters agrees satisfactorily with experimental observation.

The dynamics of photodissociation of propenal at 193 nm are studied by detecting laser-induced fluorescence of nascent fragment HCO in its transition B̃ 2A′–X̃ 2A′. Rotational states up to N=30 and K=3 of HCO X̃ 2A′ are populated and vibrational states (000), (010), and (001) are detected. The Ka=1 doublet states and the two spin states for all vibrational levels detected are nearly equally populated. Much less rotational excitation is observed than the distributions calculated on a statistical model—phase space theory. This implies that dissociation occurs from the triplet channel with a small exit barrier. Small rotational excitation arises from the repulsive part of the exit barrier and the geometry of the transition state on the triplet surface. Experimental data yield an energy partitioning with translation, rotation, and vibration of HCO at 3.0, 1.3, and 1.5 kcal/mol, respectively, in total accounting for 11.5% of available energy. These results indicate that the other fragment C2H3 has 3.2 kcal/mol of translation and 42.5 kcal/mol of internal energy; hence, most C2H3 is expected to undergo secondary dissociation to C2H2 and H. Because the appearance of HCO is faster than that calculated based on the Rice–Ramsperger–Kassel–Marcus theory, other decay pathways dominate the pathway of the radical channel from the triplet surface.

We report the ionization-detected absorption spectra of autoionizing Rydberg states converging to the (010) vibrational level of HCO+. Sharp second-photon resonances appear in transitions from first-photon-prepared originating states that have total angular momentum (less-spin) from N′=0 to 5, selected from the Σ+ and Σ− components of the (010) band of the 3pπ2Π Rydberg state. We systematically compare spectra in order to characterize observed resonances in terms of the good total angular momentum quantum number, N. Rydberg analysis establishes the convergence of series to detailed cation-core rotational quantum numbers, N+. Observed series are found to fit well with simulations employing a limited set of constant quantum defects (δ=1.062, 0.794, 0.606, 0.253, 0.015, 0.002, −0.027 and −0.076). The strengths of observed transitions as a function of initial and final total angular momentum provide a purely experimental indication of the appropriate assignment of the approximately good orbital angular momentum quantum number, l, for each series. Interactions between Rydberg orbital and core rotational angular momentum are found to conform with a coupling case intermediate between Hund’s cases (b) and (d). Splitting patterns further assign certain features according to predominant case (b) composition.