(2+1)REMPI on molecular nitrogen through the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si11.gif" display="inline" overflow="scroll"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>1</mml:mn></mml:mrow></mml:msup><mml:msubsup><mml:mrow><mml:mi mathvariant="normal">Σ</mml:mi></mml:mrow><mml:mrow><mml:mtext>g</mml:mtext></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math> (II)-state

Bominaar, J.; Schoemaecker, Coralie; Dam, Nico; Meulen, J. J. ter; Groenenboom, Gerrit C.

doi:10.1016/j.cplett.2006.12.100

Cited by 12 publications

(20 citation statements)

References 33 publications

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“…In the energy range accessible by the NIR pulse, dark states of both Rydberg and valence character have been found [38]. Of particular interest is an avoided crossing between the a 00 1 R g + Rydberg and 1 R g + (II) valence state, confirmed experimentally by considerable energetic perturbations of the observed vibrational levels of these two states [39,40]. The resulting double well potential of the mixed a 00 1 R g + Rydberg and 1 R g + (II) valence states is the only known bound dark state that is energetically resonant with the b 0 valence state via 1 NIR photon.…”

Section: Discussionmentioning

confidence: 83%

Attosecond transient absorption spectroscopy of molecular nitrogen: Vibrational coherences in the b′ 1Σ+u state

Warrick

Bækhøj

Cao

et al. 2017

Chemical Physics Letters

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Nuclear and electronic dynamics in a wavepacket comprising bound Rydberg and valence electronic states of nitrogen from 12 to 15 eV are investigated using attosecond transient absorption. Vibrational quantum beats with a fundamental period of 50 femtoseconds persist for a picosecond in the b 0 1 R + u valence state. Multi-state calculations show that these coherences result primarily from near infraredinduced coupling between the inner and outer regions of the b 0 1 R + u state potential and the dark a 00 1 R + g state. The excellent spectral and temporal resolution of this technique allows measurement of the anharmonicity of the b 0 1 R + u potential directly from the observed quantum beats.

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Section: Discussionmentioning

confidence: 83%

Attosecond transient absorption spectroscopy of molecular nitrogen: Vibrational coherences in the b′ 1Σ+u state

Warrick

Bækhøj

Cao

et al. 2017

Chemical Physics Letters

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“…REMPI schemes are usually referred to as n + m , where n and m are integers which correspond to the number of photons, of a single colour, used to pump and probe the system of interest, respectively [89–91]. When different colours are used for the pump and probe steps, this is referred to as n + m ′ [92,93].…”

Section: Methodologies: Frequency- and Time-resolved Spectroscopy In mentioning

confidence: 99%

Photophysics of sunscreen molecules in the gas phase: a stepwise approach towards understanding and developing next-generation sunscreens

2016

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The relationship between exposure to ultraviolet (UV) radiation and skin cancer urges the need for extra photoprotection, which is presently provided by widespread commercially available sunscreen lotions. Apart from having a large absorption cross section in the UVA and UVB regions of the electromagnetic spectrum, the chemical absorbers in these photoprotective products should also be able to dissipate the excess energy in a safe way, i.e. without releasing photoproducts or inducing any further, harmful, photochemistry. While sunscreens are tested for both their photoprotective capability and dermatological compatibility, phenomena occurring at the molecular level upon absorption of UV radiation are largely overlooked. To date, there is only a limited amount of information regarding the photochemistry and photophysics of these sunscreen molecules. However, a thorough understanding of the intrinsic mechanisms by which popular sunscreen molecular constituents dissipate excess energy has the potential to aid in the design of more efficient, safer sunscreens. In this review, we explore the potential of using gas-phase frequency- and time-resolved spectroscopies in an effort to better understand the photoinduced excited-state dynamics, or photodynamics, of sunscreen molecules. Complementary computational studies are also briefly discussed. Finally, the future outlook of expanding these gas-phase studies into the solution phase is considered.

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“…24 The two photon resonant state in N 2 has been observed at the a 1 ⌸ g state for 193 nm laser radiation in N 2 . 5, 13 As the ns g ͑n −1͒d g 1 ⌺ g + Rydberg series in O 2 and the a 1 ⌸ g state in N 2 lie at the same energy level, the resonant O 2 molecules occupying the Rydberg series have the ability to transfer energy to N 2 molecules during collisions to raise them to the a 1 ⌸ g state. From here an N 2 molecule can subsequently absorb a photon to reach the ionized B 2 ⌺ u + state.…”

Section: -5mentioning

confidence: 99%

“…This process is known as REMPI. 13 This process is very important for any MPI event involving three or more photons as in general the decay constant of the resonant state is much longer than the excitation lifetime within which the atom must absorb photons ͑femtoseconds as compared with nanoseconds or longer͒, and the greater number of photons needed to get above the ionization threshold the smaller the probability for ionization. For an m + k REMPI process the degree of nonlinearity will be the rate limiting process, or for m Ͼ k the degree of nonlinearity will be m. Shown in Fig.…”

Section: B Mpi and Rempimentioning

confidence: 99%

Excitational energy transfer enhancing ionization and spatial-temporal evolution of air breakdown with UV laser radiation

Hummelt

Scharer

2010

Journal of Applied Physics

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This paper examines the role multiphoton excitation of oxygen has on the ionization of nitrogen in laser air breakdown. Plasma is created by focusing a 193 nm ArF excimer laser using an 18 cm focal length lens, producing a cylindrical 540 μm wide spot of intensity 6.5 GW/cm2, well below the classical limit for collisional cascade (CC) breakdown. By spectroscopically monitoring the B Σ2u+ to X Σ2g+ transition at 391.4 nm of N2+ in N2 and O2 mixes, collisions between N2 and metastable O2 states that have undergone 1+1 absorption processes are shown to lower the degree of nonlinearity (i.e., the number of photons involved in the rate limiting multiphoton absorption process) in the ionization of N2. This process is also found to dominate the 2+1 resonant enhanced multiphoton ionization of N2 in air and be the primary source for ionization of N2 to the B Σ2u+ state. Plasma formation and evolution is also examined using a 1.3 cm focal length objective lens creating a 40 μm wide spot of intensity 1.25 TW/cm2, above the classical limit for breakdown. This plasma is imaged with a fast (1.2 ns) gating intensified charge coupled device camera. Early plasma formation is seen to be inhomogeneous in nature, and significant ion density is found to exist up to 20 μs after the laser pulse.

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(2+1)REMPI on molecular nitrogen through the 1Σg+ (II)-state

Cited by 12 publications

References 33 publications

Attosecond transient absorption spectroscopy of molecular nitrogen: Vibrational coherences in the b′ 1Σ+u state

Attosecond transient absorption spectroscopy of molecular nitrogen: Vibrational coherences in the b′ 1Σ+u state

Photophysics of sunscreen molecules in the gas phase: a stepwise approach towards understanding and developing next-generation sunscreens

Excitational energy transfer enhancing ionization and spatial-temporal evolution of air breakdown with UV laser radiation

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