Достижение субпикосекундного временного разрешения при исследовании процессов анизотропной релаксации биологических молекул

Probe beam dichroism and birefringency occurring in the excited states of polyatomic molecules under excitation with two femtosecond laser pulses have been theoreticaly studied as a function of delay between the pulses. General expressions describing the change of intensity and polarization of the probe laser pulse passed through the solution of arbitrary polyatomic molecules at any initital polarization of the laser pulses have been derived using the spherical tensor approach. The expressions take into account the coherence in excited molecule vibrational states and decay of these states due to vibrational relaxation, rotational diffusion, and radiative transitions. The expressions describe the effects of probe beam linear dichroism and birefringency occurring in molecular excited states. As shown, under certain conditions both effects can be observed simultaneously. It has been concluded that within the geometry of almost collinear propagation of the pump and probe laser pulses through the molecular sample the contributions from linear dichroism and birefringency can be completely separated from each other by an appropriate choice of the polarization analyzer placed in front of the photodetector. The obtained expressions were applied for description of the signals that can be recorded experimentally by means of the polarization-modulation scheme developed in the recent author's publication (Gorbunova et al,Phys. Chem. Chem. Phys. 2020, Vol. 22, 18155−18168). The theory predicts that the modulated signals of dichroism and birefringency appear in quadrature with respect to the double frequency reference modulation signal.

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Ultrafast Pump-Probe Spectroscopy of Finite-Sized Neutral Iron Oxide Clusters

10.26434/chemrxiv.12774629.v1 ◽

2020 ◽

Author(s):

Jacob Garcia ◽

ryan shaffer ◽

Scott Sayres

Keyword(s):

Excited State ◽

Iron Oxide ◽

Cluster Size ◽

Iron Oxidation ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Laser Vaporization ◽

Relative Population ◽

Pump Probe ◽

Probe Spectroscopy

<div><p>Neutral iron oxide clusters (Fe<sub>n</sub>O<sub>m</sub>, n,m ≤ 16) are produced in a laser vaporization source using O<sub>2</sub>gas seeded in He. The neutral clusters are ionized with a sequence of femtosecond laser pulses and detected using time-of-flight mass spectrometry. Small clusters are confirmed to be most prominant in the stoichiometric (n = m) distribution, with m = n + 1 clusters observed above n = 4. Pump-probe spectroscopy is employed to study the dynamics of an electron transfer from an oxygen orbital to an iron nonbonding orbital of iron oxide clusters that is driven by absorption of a 400 nm photon. A bifurcation of the initial wavepacket occurs, where a femtosecond component is attributed to electron relaxation assisted through internuclear vibrational relaxation, and a slow relaxation shows the formation of a bound excited state. The lifetime and relative ratio of the two pathways depends on both the cluster size and iron oxidation state. The femtosecond lifetime decreases with increased cluster size until a saturation timescale is achieved at n > 5. The relative population of the long-lived excited state decreases with cluster size and suggests that the excited electron remains on the Fe atom for > 20 ps. </p></div>

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Ultrafast Pump-Probe Spectroscopy of Finite-Sized Neutral Iron Oxide Clusters

10.26434/chemrxiv.12774629 ◽

2020 ◽

Author(s):

Jacob Garcia ◽

ryan shaffer ◽

Scott Sayres

Keyword(s):

Excited State ◽

Iron Oxide ◽

Cluster Size ◽

Iron Oxidation ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Laser Vaporization ◽

Relative Population ◽

Pump Probe ◽

Probe Spectroscopy

<div><p>Neutral iron oxide clusters (Fe<sub>n</sub>O<sub>m</sub>, n,m ≤ 16) are produced in a laser vaporization source using O<sub>2</sub>gas seeded in He. The neutral clusters are ionized with a sequence of femtosecond laser pulses and detected using time-of-flight mass spectrometry. Small clusters are confirmed to be most prominant in the stoichiometric (n = m) distribution, with m = n + 1 clusters observed above n = 4. Pump-probe spectroscopy is employed to study the dynamics of an electron transfer from an oxygen orbital to an iron nonbonding orbital of iron oxide clusters that is driven by absorption of a 400 nm photon. A bifurcation of the initial wavepacket occurs, where a femtosecond component is attributed to electron relaxation assisted through internuclear vibrational relaxation, and a slow relaxation shows the formation of a bound excited state. The lifetime and relative ratio of the two pathways depends on both the cluster size and iron oxidation state. The femtosecond lifetime decreases with increased cluster size until a saturation timescale is achieved at n > 5. The relative population of the long-lived excited state decreases with cluster size and suggests that the excited electron remains on the Fe atom for > 20 ps. </p></div>

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Nonperturbative generation of above-threshold harmonics from pre-excited argon atoms in intense mid-infrared laser fields

High Power Laser Science and Engineering ◽

10.1017/hpl.2017.26 ◽

2017 ◽

Vol 5 ◽

Cited By ~ 2

Author(s):

Guihua Li ◽

Hongqiang Xie ◽

Ziting Li ◽

Jinping Yao ◽

Wei Chu ◽

...

Keyword(s):

Excited State ◽

Femtosecond Laser ◽

Pulse Energy ◽

Laser Pulses ◽

Infrared Laser ◽

Femtosecond Laser Pulses ◽

Probe Laser ◽

Laser Fields ◽

Mid Infrared ◽

Highly Nonlinear

We experimentally investigate the generation of above-threshold harmonics completely from argon atoms on an excited state using mid-infrared femtosecond laser pulses. The highly nonlinear dependences of the observed signal on the pulse energy and polarization of the probe laser pulses indicate its nonperturbative characteristic.

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Renilla reniformis bioluminescence: luciferase-catalyzed production of nonradiating excited states from luciferin analogs and elucidation of the excited state species involved in energy transfer to Renilla green fluorescent protein

Biochemistry ◽

10.1021/bi00578a011 ◽

1979 ◽

Vol 18 (11) ◽

pp. 2204-2210 ◽

Cited By ~ 47

Author(s):

Russell C. Hart ◽

John C. Matthews ◽

Kazuo Hori ◽

Milton J. Cormier

Keyword(s):

Energy Transfer ◽

Excited State ◽

Green Fluorescent Protein ◽

Excited States ◽

Fluorescent Protein ◽

Renilla Reniformis ◽

Green Fluorescent

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Understanding the Seeding Pulse-Induced Optical Amplification in N 2 + Pumped by 800 NM Femtosecond Laser Pulses

Photonics ◽

10.3390/photonics7040099 ◽

2020 ◽

Vol 7 (4) ◽

pp. 99

Author(s):

Zhengquan Fan ◽

Xiang Zhang ◽

Qi Lu ◽

Yu Luo ◽

Qingqing Liang ◽

...

Keyword(s):

Femtosecond Laser ◽

Optical Gain ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Time Resolved ◽

Optical Amplification ◽

Pump Probe ◽

Amplification Process ◽

Energy Amplification

Nitrogen ions pumped by intense femtosecond laser pulses present an optical gain at 391.4 nm, evident by energy amplification of an injected resonant seeding pulse. We report a time-resolved measurement of the amplification process with seeding pulses having varying intensities. It is found that the amplification factor depends on the intensity of the seeding pulse and the effective temporal window for the optical gain becomes longer by applying more intense seeding pulses. These two features are in sharp contrast with classic pump-probe experiments, pinpointing the crucial role of macroscopic coherence and its dynamics during the lasing process. We further measure the temporal profile of the amplified emission for seeding pulse injected at different time delays. A complicated temporal behavior is observed, which highlights the nature of the superfluorescence.

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Study of Millimeter-Wave Rotational Spectra ofTrioxane in Ground, v(A), v1(E) = 1 and v2(E) = 1 States

E-Journal of Chemistry ◽

10.1155/2009/692791 ◽

2009 ◽

Vol 6 (s1) ◽

pp. S259-S279 ◽

Cited By ~ 1

Author(s):

Masoud Motamedi ◽

Najmehalsadat Khademi

Keyword(s):

Excited State ◽

Excited States ◽

Millimeter Wave ◽

Ground State ◽

Vibrational States ◽

Rotational Spectra ◽

First Time

The millimeter-wave rotational spectra of the ground and excited vibrational states v(A), v1(E) =1 and v2(E ) =1 of the oblate symmetric top molecule, (CH2O)3, have been analyzed again. The B0= 5273.25747MHz, DJ= 1.334547 kHz, DJk= -2.0206 kHz, HJ(-1.01 mHz), HJK(-3.80 mHz), and HKJ(4.1 mHz) have been determined for ground state. For non degenerate excited state, vA(1), the B = 5260.227723 MHz and DJand DJKwere determined 1.27171 kHz and -1.8789 kHz respectively. The 1=±1 series have been assigned in two different excited states v1(E) =1 and v2(E) =1.Most of the parameters were determined with higher accuracy compare with before. For the v2(E) =1 state the Cζ=-1940.54(11) MHz and qJ= 0.0753 (97) kHz were determined for the first time.

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Temperature dependent iodide oxidation by MLCT excited states

Dalton Transactions ◽

10.1039/c4dt01683a ◽

2014 ◽

Vol 43 (47) ◽

pp. 17856-17863 ◽

Cited By ~ 6

Author(s):

Atefeh Taheri ◽

Gerald J. Meyer

Keyword(s):

Excited State ◽

Excited States ◽

Temperature Dependent ◽

Iodide Oxidation ◽

First Time

Temperature dependent excited state iodide oxidation by two heteroleptic Ru polypyridyl compounds was quantified for the first time.

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Laser Ion Kinetics: Dynamics of Intramolecular Reactions in Substituted Benzalacetones

European Journal of Mass Spectrometry ◽

10.1255/ejms.334 ◽

2000 ◽

Vol 6 (2) ◽

pp. 143-152 ◽

Cited By ~ 1

Author(s):

R. Heinicke ◽

C. Grun ◽

J. Grotemeyer

Keyword(s):

Femtosecond Laser ◽

Mass Spectrometer ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Photon Absorption ◽

Single Shot ◽

Pump Probe ◽

Intramolecular Reactions ◽

The Stability ◽

Fragmentation Processes

Measurements of a single shot femtosecond laser pump-probe technique on substituted benzalacetones are reported. The technique is based on counter propagating femtosecond laser pulses in a supersonic beam of low density of sample molecules and simultaneous probe detection by ion or fragment ion formation through a reflectron time-of-flight mass spectrometer. It will be shown that the range of the pump-probe delays covers the time span between 100 fs and 10 ps depending on the pulse width of the laser used and the stability of the voltages of the mass spectrometer. The application of this technique to medium-sized organic molecules reveals some insight into the electron transfer process during ionisation through a 1 + 1 multi-photon absorption procedure. Furthermore it is demonstrated that this technique is also applicable to the investigation of ultra-fast isomerisation and fragmentation processes.

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Time-Resolved Resonance Raman Spectroscopy of Excited-State Porphyrins

Laser Chemistry ◽

10.1155/1999/82824 ◽

1999 ◽

Vol 19 (1-4) ◽

pp. 271-274 ◽

Cited By ~ 4

Author(s):

S. E. J. Bell ◽

J. H. Rice ◽

J. J. McGarvey ◽

R. E. Hester ◽

J. N. Moore ◽

...

Keyword(s):

Excited State ◽

Excited States ◽

Laser Excitation ◽

Resonance Raman Spectroscopy ◽

Resonance Raman ◽

Laser Pulses ◽

Significant Shift ◽

Time Resolved ◽

Two Component ◽

Absorbance Difference

Time-resolved resonance Raman (TR3) and absorbance difference studies of the excited states of Cu(TPP) (TPP=5,10,15,20-tetraphenylporphyrin) have been carried out with < 10 ps times resolution in THF and pyridine solvents. In THF the distinctive transient Raman bands in the ν2 and ν4 regions, previously observed with ns laser pulses, grow in the first 55 ps before decaying in 100's of ps. The ∆A spectra also show biphasic decay. This behaviour is associated with attack by solvent on the 4-coordinate excited state to form the longer lived species observed in TR3 experiments.In pyridine two component decay is also observed but it is the shorter-lived species which gives the transient Raman bands seen previously with ns laser excitation. This state is different from that seen in THF. At 5 ps delay ν4 is broader than in the ground state and, more importantly, there is a significant shift in the two pyridine bands at ca. 1000 cm-1. This implies a significant involvement of the pyridine-based orbitals in the excited state.

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