Control of Giant Breathing Motion in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi mathvariant="normal">C</mml:mi><mml:mn>60</mml:mn></mml:msub></mml:math>with Temporally Shaped Laser Pulses

Laarmann, Tim; Shchatsinin, Ihar; Stalmashonak, Andrei; Boyle, M.; Zhavoronkov, N.; Handt, J.; Schmidt, R.; Schulz, C. P.; Hertel, I. V.

doi:10.1103/physrevlett.98.058302

Cited by 72 publications

(58 citation statements)

References 29 publications

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“…Finally, as demonstrated in Fig. 1(f), when the pump repetition rate was tuned to the middle of the RBM frequencies for (11,3) and (10,5) nanotubes, both nanotubes contributed. The accuracy of selectivity depends on the number of pulses in the tailored pulse train as well as on the distribution of chiralities in the nanotube ensemble.…”

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confidence: 98%

“…There is a π phase shift between the 780 nm and 810 nm data. These three wavelengths correspond to below, at, and above the second exciton resonance, respectively, of (11,3) to perform detailed studies of their excited states. For example, by placing a series of 10-nm band pass filters in the probe path before the detector, we can measure the wavelength-dependence of RBM-induced transmission changes to understand how the diameter change during RBM oscillations modifies the band structure.…”

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confidence: 99%

“…Specifically, we have utilized the techniques of femtosecond pulse shaping [9,10,11] in ultrafast pump-probe spectroscopy of SWNTs to selectively excite the coherent lattice vibrations [12,13] of the radial breathing mode (RBM) of specific chiralities. The excitation spectra of such coherent phonons (CPs) provide chirality-specific information on the processes of light absorption, phonon generation, and phonon-induced band structure modulations in unprecedented detail.…”

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Chirality-Selective Excitation of Coherent Phonons in Carbon Nanotubes by Femtosecond Optical Pulses

et al. 2009

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Using pre-designed trains of femtosecond optical pulses, we have selectively excited coherent phonons of the radial breathing mode of specific-chirality single-walled carbon nanotubes within an ensemble sample. By analyzing the initial phase of the phonon oscillations, we prove that the tube diameter initially increases in response to ultrafast photoexcitation. Furthermore, from excitation profiles, we demonstrate that an excitonic absorption peak of carbon nanotubes periodically oscillates as a function of time when the tube diameter undergoes radial breathing mode oscillations.PACS numbers: 78.67. Ch,71.35.Ji, Single-walled carbon nanotubes (SWNTs), hollow onedimensional nanostructures with unique electronic, mechanical, and optical properties, come in a variety of species, or chiralities. Some of them are metallic and others semiconducting, depending on their chiral indices (n,m) [1,2,3]. This diversity, while making them such unusual nanomaterials, often makes it challenging to extract reliable parameters on chirality-dependent properties from experimental results on ensemble samples. Currently, there are world-wide efforts on SWNT purification, separation, and enrichment, producing promising results [4,5,6,7,8]. However, a standard for fabrication of these samples has yet to be established.Here, we present a novel method that allows us to study single-chirality nanotubes even though the sample contains nanotubes of many different chiralities. Specifically, we have utilized the techniques of femtosecond pulse shaping [9,10,11] in ultrafast pump-probe spectroscopy of SWNTs to selectively excite the coherent lattice vibrations [12,13] of the radial breathing mode (RBM) of specific chiralities. The excitation spectra of such coherent phonons (CPs) provide chirality-specific information on the processes of light absorption, phonon generation, and phonon-induced band structure modulations in unprecedented detail. In particular, the excitation-energy-dependence of the phase of the CP oscillations provides direct, time-domain evidence that band gap oscillations follow the diameter oscillations in the RBM coherent phonon mode.The sample studied was a micelle-suspended SWNT solution, where the SWNTs (HiPco batch HPR 104) were suspended as individuals with sodium cholate [14]. The optical setup was that of standard degenerate pumpprobe spectroscopy, but chirality selectivity was achieved by using multiple pulse trains, with a pulse-to-pulse interval corresponding to the period of a specific RBM mode. Among different species of nanotubes, those having RBM frequencies that are matched to the repetition rate of multiple pulse trains will generate large amplitude coherent oscillations with increasing oscillatory response to each pulse, while others will have diminished coherent responses [15,16,17]. The tailoring of multiple pulse trains from femtosecond pulses was achieved using the pulse-shaping technique described elsewhere [10]. Pulse trains are incident on an ensemble of nanotubes as a pump beam, and coherent RBM osc...

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Chirality-Selective Excitation of Coherent Phonons in Carbon Nanotubes by Femtosecond Optical Pulses

et al. 2009

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“…Of similar interest is the role of intermediate electronically excited states in the absorption process [11][12][13] and efficient coupling of electronic to nuclear motion. [14][15][16][17][18][19] Related to these "hot topics" in current femtosecond laser-based research on isolated fullerenes is the investigation of characteristic coupling times for the energy flow within the electronic system and into nuclear degrees of freedom. One may speculate that for C 60 with its 240 valence electrons and 174 vibrational degrees of freedom, models used in metal or semiconductor physics might give some useful insights into the time scales relevant for energy redistribution in C 60 : we argue that molecular physics meets solid state physics when studying strong-field effects induced in this special hollow semiconductor nanosphere.…”

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confidence: 99%

Ultrafast energy redistribution in C60 fullerenes: A real time study by two-color femtosecond spectroscopy

Shchatsinin

Laarmann

Zhavoronkov

et al. 2008

The Journal of Chemical Physics

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Strong-field excitation and energy redistribution dynamics of C 60 fullerenes are studied by means of time-resolved mass spectrometry in a two-color femtosecond pump-probe setup. Resonant pre-excitation of the electronic system via the first dipole-allowed HOMO→ LUMO+ 1͑t 1g ͒ ͑HOMO denotes highest occupied molecular orbital and LUMO denotes lowest unoccupied molecular orbital͒ transition with ultrashort 25 fs pulses at 399 nm of some 10 12 W cm −2 results in a highly nonequilibrium distribution of excited electrons and vibrational modes in the neutral species. The subsequent coupling among the electronic and nuclear degrees of freedom is monitored by probing the system with time-delayed 27 fs pulses at 797 nm of some 10 13 W cm −2 . Direct information on the characteristic relaxation time is derived from the analysis of transient singly and multiply charged parent and fragment ion signals as a function of pump-probe delay and laser pulse intensity. The observed relaxation times el Ӎ 60-400 fs are attributed to different microcanonical ensembles prepared in the pre-excitation process and correspond to different total energy contents and energy sharing between electronic and vibrational degrees. The characteristic differences and trends allow one to extract a consistent picture for the formation dynamics of ions in different charge states and their fullerenelike fragments and give evidence to collective effects in multiple ionization such as plasmon-enhanced energy deposition.

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“…͑2͒ and ͑3͒, and in qualitative agreement with other simulations 12 and experiment. [24][25][26][27][28] In Fig. 3, the agreement between the predictions of the analytical model ͑curves͒ and the completely independent DFT-based simulations ͑points͒ is truly remarkable.…”

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confidence: 88%

Maximum relative excitation of a specific vibrational mode via optimum laser-pulse duration

et al. 2010

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For molecules and materials responding to femtosecond-scale optical laser pulses, we predict maximum relative excitation of a Raman-active vibrational mode with period T when the pulse has a full-width-at-halfmaximum duration Ϸ 0.42T. This result follows from a general analytical model, and is precisely confirmed by detailed density-functional-based dynamical simulations for C 60 and a carbon nanotube, which include anharmonicity, nonlinearity, no assumptions about the polarizability tensor, and no averaging over rapid oscillations within the pulse. The mode specificity is, of course, best at low temperature and for pulses that are electronically off-resonance, and the energy deposited in any mode is proportional to the fourth power of the electric field. For a quarter century there has been considerable interest in optimizing the vibrational response of molecules and materials to ultrafast laser pulses. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] This problem is directly relevant to the broader issue of coherent control in physical, chemical, [16][17][18][19] and biological 20-23 systems.Here we consider excitation via impulsive stimulated Raman scattering and related techniques using femtosecondscale optical pulses. We find that the optimum full-width-athalf-maximum ͑FWHM͒ pulse duration for exciting a specific vibrational mode with angular frequency 2 / T is given by Ϸ 0.42T. Our prediction results from a general analytical model, and is precisely confirmed by completely independent density-functional-based simulations for C 60 24-28 and a small carbon nanotube. [29][30][31] Unlike the model, these simulations include anharmonic effects in the vibrations, nonlinear effects in the response to the applied field and no simplifying assumptions about the electronic polarizability tensor.Our general model consists of the following: ͑1͒ the electric field has the formwith ӷ / and ប off resonance. Since the oscillations of sin 2 ͑ t + ␦͒ will average out to 1/2 over a period that is short compared to the response time of the vibrating nuclei, we will actually replace the square of Eq. ͑1͒ by the envelope functionwith Ē 0 2 = E 0 2 / 2. This form has the following nice features: 32 ͑i͒ the duration is finite and need not be truncated. ͑ii͒ The FWHM duration is exactly half the full duration 2 . ͑iii͒ A plot reveals that it closely resembles a Gaussian. ͑iv͒ The slope is zero at beginning and end. ͑2͒ The initial conditions Q k ͑0͒ = Q k ͑0͒ = 0 are imposed on the normal-mode coordinates Q k ͑t͒. This approximation is valid for the expectation value below Eq. ͑4͒ at low temperature, or an ensemble average at higher temperature, in the linearized Eq. ͑3͒. ͑3͒ The equation of motion is given by the standard ͑Placzek͒ model for Raman-active modes 8,21,33where the anharmonic and damping terms ͑in the normalmode coordinates Q k ͒, nonlinear terms ͓in the electric field E͑t͔͒, and off-diagonal terms ͑in the polarizability tensor ␣͒ have been neglected, with the electric dipole moment given by tot = + ind , ind = ␣ · ...

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Control of Giant Breathing Motion inC60with Temporally Shaped Laser Pulses

Cited by 72 publications

References 29 publications

Chirality-Selective Excitation of Coherent Phonons in Carbon Nanotubes by Femtosecond Optical Pulses

Chirality-Selective Excitation of Coherent Phonons in Carbon Nanotubes by Femtosecond Optical Pulses

Ultrafast energy redistribution in C60 fullerenes: A real time study by two-color femtosecond spectroscopy

Maximum relative excitation of a specific vibrational mode via optimum laser-pulse duration

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