Exploring femtosecond laser ablation in single-particle aerosol mass spectrometry

Abstract. Size, composition, and mixing state of individual aerosol particles can be analysed in real time using single-particle mass spectrometry (SPMS). In SPMS, laser ablation is the most widely used method for desorption and ionization of particle components, often realizing both in one single step. Excimer lasers are well suited for this task due to their relatively high power density (107–1010 W cm−2) in nanosecond (ns) pulses at ultraviolet (UV) wavelengths and short triggering times. However, varying particle optical properties and matrix effects make a quantitative interpretation of this analytical approach challenging. In atmospheric SPMS applications, this influences both the mass fraction of an individual particle that is ablated, as well as the resulting mass spectral fragmentation pattern of the ablated material. The present study explores the use of shorter (femtosecond, fs) laser pulses for atmospheric SPMS. Its objective is to assess whether the higher laser power density of the fs laser leads to a more complete ionization of the entire particle and higher ion signal and thus improvement in the quantitative abilities of SPMS. We systematically investigate the influence of power density and pulse duration on airborne particle (polystyrene latex, SiO2, NH4NO3, NaCl, and custom-made core-shell particles) ablation and reproducibility of mass spectral signatures. We used a laser ablation aerosol time-of-flight single-particle mass spectrometer (LAAPTOF, AeroMegt GmbH), originally equipped with an excimer laser (wavelength 193 nm, pulse width 8 ns, pulse energy 4 mJ), and coupled it to an fs laser (Spectra Physics Solstice-100F ultrafast laser) with similar pulse energy but longer wavelengths (266 nm with 100 fs and 0.2 mJ, 800 nm with 100 fs and 3.2 mJ). We successfully coupled the free-firing fs laser with the single-particle mass spectrometer employing the fs laser light scattered by the particle to trigger mass spectra acquisition. Generally, mass spectra exhibit an increase in ion intensities (factor 1 to 5) with increasing laser power density (∼ 109 to ∼ 1013 W cm−2) from ns to fs laser. At the same time, fs-laser ablation produces spectra with larger ion fragments and ion clusters as well as clusters with oxygen, which does not render spectra interpretation more simple compared to ns-laser ablation. The idea that the higher power density of the fs laser leads to a more complete particle ablation and ionization could not be substantiated in this study. Quantification of ablated material remains difficult due to incomplete ionization of the particle. Furthermore, the fs-laser application still suffers from limitations in triggering it in a useful time frame. Further studies are needed to test potential advantages of fs- over ns-laser ablation in SPMS.

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Exploring femtosecond laser ablation in single particle aerosol mass spectrometry

10.5194/amt-2017-357 ◽

2017 ◽

Cited By ~ 1

Author(s):

Ramakrishna Ramisetty ◽

Ahmed Abdelmonem ◽

Xiaoli Shen ◽

Harald Saathoff ◽

Thomas Leisner ◽

...

Keyword(s):

Mass Spectrometry ◽

Laser Ablation ◽

Power Density ◽

Single Particle ◽

Pulse Energy ◽

Particle Mass ◽

Fragmentation Pattern ◽

Mass Spectral ◽

Custom Made ◽

Fs Laser

Abstract. Size, composition, and mixing state of individual aerosol particles can be analysed in real time using single particle mass spectrometry (SPMS). In SPMS, laser ablation is the most widely used method for desorption and ionization of particle components, often realizing both in one single step. Excimer lasers are well suited for this task due to their relatively high power density (107 W cm−2–1010 W cm−2) in nanosecond (ns) pulses at ultraviolet (UV) wavelengths, and short triggering times. However, varying particle optical properties and matrix effects make a quantitative interpretation of this analytical approach challenging. In atmospheric SPMS applications, this influences both the mass fraction of an individual particle that gets ablated, as well as the resulting mass spectral fragmentation pattern of the ablated material. The goal of the present study is to explore the use of shorter (femtosecond, fs) laser pulses for atmospheric SPMS, and to systematically investigate the influence of power density and pulse duration on airborne particle (polystyrene latex, SiO2, NH4NO3, NaCl, and custom-made core-shell particles) ablation and reproducibility of mass spectral signatures. We used a laser ablation aerosol time-of-flight single particle mass spectrometer (LAAPTOF, AeroMegt GmbH), originally equipped with an excimer laser (wavelength 193 nm, pulse width 8 ns, pulse energy 4 mJ), and coupled it to an fs-laser (Spectra Physics Solstice-100F ultrafast laser) with similar pulse energy, but longer wavelengths (266 nm with 100 fs and 0.2 mJ, 800 nm with 100 fs and 4 mJ, respectively). Generally, mass spectra exhibit an increase in ion intensities (factor 1 to 5) with increasing laser power density (~ 108 W cm−2 to ~ 1013 W cm−2) from ns- to fs-laser. At the same time, fs-laser ablation produces spectra with larger ion fragments and ion clusters, as well as clusters with oxygen, which does not render spectra interpretation more simple compared to ns-laser ablation. Quantification of ablated material remains difficult due to incomplete ionization of the particle. Furthermore, the fs-laser application still suffers from limitations in triggering it in a useful timeframe. Further tests are needed to test potential advantages of fs- over ns-laser ablation in atmospheric SPMS.

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Carbon nanodots featuring efficient FRET for two-photon photodynamic cancer therapy with a low fs laser power density

Biomaterials ◽

10.1016/j.biomaterials.2014.07.063 ◽

2014 ◽

Vol 35 (34) ◽

pp. 9372-9381 ◽

Cited By ~ 84

Author(s):

Jing Wang ◽

Zehui Zhang ◽

Shuai Zha ◽

Yinyan Zhu ◽

Peiyi Wu ◽

...

Keyword(s):

Cancer Therapy ◽

Power Density ◽

Laser Power ◽

Laser Power Density ◽

Carbon Nanodots ◽

Two Photon ◽

Photodynamic Cancer Therapy ◽

Fs Laser

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The Effect of Laser Power Density on the Observed Products of Combustion of Gasoline Using Laser-Induced Thermal Desorption with Fourier Transform Mass Spectrometry

Journal of Forensic Sciences ◽

10.1111/1556-4029.12021 ◽

2012 ◽

Vol 58 ◽

pp. S192-S198

Author(s):

Katherine D. Hutches ◽

Diana Wang ◽

Donald P. Land

Keyword(s):

Mass Spectrometry ◽

Fourier Transform ◽

Power Density ◽

Thermal Desorption ◽

Laser Power ◽

Fourier Transform Mass Spectrometry ◽

Laser Power Density

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Laser Desorption Mass Spectrometry of Complex Biomolecules at High Laser Power Density

Springer Series in Chemical Physics - Secondary Ion Mass Spectrometry SIMS IV ◽

10.1007/978-3-642-82256-8_95 ◽

1984 ◽

pp. 370-373 ◽

Cited By ~ 5

Author(s):

B. Lindner ◽

U. Seydel

Keyword(s):

Mass Spectrometry ◽

Power Density ◽

Laser Power ◽

Laser Desorption ◽

Laser Power Density ◽

Laser Desorption Mass Spectrometry ◽

Desorption Mass Spectrometry ◽

High Laser Power ◽

High Laser

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Development and characterization of a single particle laser ablation mass spectrometer (SPLAM) for organic aerosol studies

Atmospheric Measurement Techniques ◽

10.5194/amt-5-225-2012 ◽

2012 ◽

Vol 5 (1) ◽

pp. 225-241 ◽

Cited By ~ 10

Author(s):

F. Gaie-Levrel ◽

S. Perrier ◽

E. Perraudin ◽

C. Stoll ◽

N. Grand ◽

...

Keyword(s):

Laser Ablation ◽

Detection Limit ◽

Mass Spectrometer ◽

Single Particle ◽

Mass Spectra ◽

Diode Lasers ◽

Optical Detection ◽

Organic Aerosol ◽

Polystyrene Latex ◽

Particle Mass

Abstract. A single particle instrument was developed for real-time analysis of organic aerosol. This instrument, named Single Particle Laser Ablation Mass Spectrometry (SPLAM), samples particles using an aerodynamic lens system for which the theoretical performances were calculated. At the outlet of this system, particle detection and sizing are realized by using two continuous diode lasers operating at λ = 403 nm. Polystyrene Latex (PSL), sodium chloride (NaCl) and dioctylphtalate (DOP) particles were used to characterize and calibrate optical detection of SPLAM. The optical detection limit (DL) and detection efficiency (DE) were determined using size-selected DOP particles. The DE ranges from 0.1 to 90% for 100 and 350 nm DOP particles respectively and the SPLAM instrument is able to detect and size-resolve particles as small as 110–120 nm. During optical detection, particle scattered light from the two diode lasers, is detected by two photomultipliers and the detected signals are used to trigger UV excimer laser (λ = 248 nm) used for one-step laser desorption ionization (LDI) of individual aerosol particles. The formed ions are analyzed by a 1 m linear time-of-flight mass spectrometer in order to access to the chemical composition of individual particles. The TOF-MS detection limit for gaseous aromatic compounds was determined to be 0.85 × 10−15 kg (∼4 × 103 molecules). DOP particles were also used to test the overall operation of the instrument. The analysis of a secondary organic aerosol, formed in a smog chamber by the ozonolysis of indene, is presented as a first application of the instrument. Single particle mass spectra were obtained with an effective hit rate of 8%. Some of these mass spectra were found to be very different from one particle to another possibly reflecting chemical differences within the investigated indene SOA particles. Our study shows that an exhaustive statistical analysis, over hundreds of particles, and adapted reference mass spectra are further needed to understand the chemical meaning of single particle mass spectra of chemically complex submicrometer-sized organic aerosols.

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Development of an automatic linear calibration method for high-resolution single-particle mass spectrometry: improved chemical species identification for atmospheric aerosols

Atmospheric Measurement Techniques ◽

10.5194/amt-13-4111-2020 ◽

2020 ◽

Vol 13 (8) ◽

pp. 4111-4121

Author(s):

Shengqiang Zhu ◽

Lei Li ◽

Shurong Wang ◽

Mei Li ◽

Yaxi Liu ◽

...

Keyword(s):

Mass Spectrometry ◽

High Resolution ◽

Single Particle ◽

Mass Spectra ◽

Calibration Method ◽

Particle Mass ◽

Sea Spray ◽

Linear Calibration ◽

Ambient Aerosol ◽

Sea Spray Aerosol

Abstract. The mass resolution of laser desorption ionization (LDI) single-particle aerosol mass spectrometry (SPAMS) is usually low (∼500), which has been greatly improved by the recent development of the delayed ion extraction technique. However, due to large fluctuations among LDI processes during each laser shot, accurate calibration of the mass-to-charge ratio for high-resolution SPAMS (HR-SPAMS) spectra is challenging. Here we developed an automatic linear calibration method to improve the accuracy of mass-to-charge (m∕z) measurement for single atmospheric aerosol particles. Laboratory-generated sea spray aerosol and atmospheric ambient aerosol were tested. After the calibration, the fluctuation ranges of the reference ions' (e.g., Pb+ and SO4+) m∕z reaches ±0.018 for sea spray aerosol and ±0.024 for ambient aerosol in average mass spectra. With such m∕z accuracy, the HR-SPAMS spectra of sea spray aerosol can easily identify elemental compositions of organic peaks, such as Cx, CxHy and CxHyOz. While the chemical compositions of ambient aerosols are more complicated, CxHy, CxHyOz and CNO peaks can also be identified based on their accurate mass. With the improved resolution, the time series of peaks with small m∕z differences can be separated and measured. In addition, it is also found that applying high-resolution data with enhanced mass calibration can significantly affect particle classification (identification) using the ART-2a algorithm, which classify particles based on similarities among single-particle mass spectra.

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Development of an Automatic Linear Calibration Method for High Resolution Single Particle Mass Spectrometry: Improved Chemical Species Identification for Atmospheric Aerosols

10.5194/amt-2019-489 ◽

2020 ◽

Author(s):

Shengqiang Zhu ◽

Lei Li ◽

Shurong Wang ◽

Mei Li ◽

Yaxi Liu ◽

...

Keyword(s):

Mass Spectrometry ◽

High Resolution ◽

Single Particle ◽

Mass Spectra ◽

Calibration Method ◽

Particle Mass ◽

Sea Spray ◽

Linear Calibration ◽

Ambient Aerosol ◽

Sea Spray Aerosol

Abstract. The mass resolution of laser desorption ionization (LDI) single particle aerosol mass spectrometry (SPAMS) is usually low (~500), which has been greatly improved by recent development of delayed ion extraction technique. However, due to large fluctuations among LDI processes during each laser shot, accurate calibration of mass-to-charge ratio for high resolution SPAMS spectra is challenging. Here we developed an automatic linear calibration method to improve the accuracy of mass-to-charge (m/z) measurement for single atmospheric aerosol particles. Laboratory generated sea spray aerosol and atmospheric ambient aerosol were tested. After the calibration, the fluctuation ranges of the reference ions (e.g. Pb+ and SO4+) m/z reaches ±0.018 for sea spray aerosol and ±0.024 for ambient aerosol in average mass spectra. With such m/z accuracy, the HR-SPAMS spectra of sea spray aerosol can easily identify elemental compositions of organic peaks, such as Cx, CxHy and CxHyOz. While the chemical compositions of ambient aerosols are more complicated, CxHy, CxHyOz and CNO peaks can also be identified based on their accurate mass. With the improved resolution, the time series of peaks with small m/z differences can be separated and measured. In addition, it is also found that applying high resolution data with enhanced mass calibration can significantly affect particle classification (identification) using the ART-2a algorism, which classify particles based on similarities among single particle mass spectra.

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Improved identification of primary biological aerosol particles using single particle mass spectrometry

10.5194/acp-2016-1119 ◽

2016 ◽

Author(s):

Maria A. Zawadowicz ◽

Karl D. Froyd ◽

Daniel M. Murphy ◽

Daniel J. Cziczo

Keyword(s):

Mass Spectrometry ◽

Single Particle ◽

Mass Spectra ◽

Aerosol Particles ◽

Particle Mass ◽

Cloud Formation ◽

Single Particle Mass Spectrometry ◽

Ambient Data ◽

By Products ◽

Biological Aerosol Particles

Abstract. Measurements of primary biological aerosol particles, especially at altitudes relevant to cloud formation, are scarce. Single particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols using SPMS. We show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodology to differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to ambient data collected at Storm Peak Laboratory to show that 0.04–0.3 % of particles in the 200–3000 nm aerodynamic diameter range were identified as bioaerosol.

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Hard Amorphous Carbon Films Deposited by ArF Pulse Laser Ablation of Graphite at Room Temperature

MRS Proceedings ◽

10.1557/proc-270-451 ◽

1992 ◽

Vol 270 ◽

Cited By ~ 1

Author(s):

Fulin Xiong ◽

R. P. H. Chang

Keyword(s):

Laser Ablation ◽

Power Density ◽

Amorphous Carbon ◽

Laser Power ◽

Room Temperature ◽

High Vacuum ◽

Carbon Films ◽

Laser Wavelength ◽

Laser Power Density ◽

Amorphous Carbon Films

ABSTRACTHard amorphous carbon films have been deposited by ArF pulsed laser ablation of graphite at room temperature, with the laser power density of 5x108 W/cm2. The films prepared in the high vacuum environment possess remarkable diamond-like properties with a hardness up to 38 GPa and an optical energy band gap of 2.4 eV. The properties of the films doped with nitrogen vary with the nitrogen content, but improve interface adhesion, resulting in the extension of the film thickness limit to a greater range. The results suggest that the properties of the laser ablation deposited diamond-like carbon films depend not only on the laser power density, but also strongly on the laser wavelength or photon energy.

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